Plant a shrub or tree; true roots +, origin endogeneous, root cap +, apex multicellular; endodermis +; shoot apical meristem multicellular; lateral meristems +, cork cambium producing cork abaxially, vascular cambium producing phloem abaxially and xylem adaxially; lamina with mean venation density 1.8 mm/mm2 (to 5 mm/mm2).
EXTANT SEED PLANTS/SPERMATOPHYTA
Plant woody, evergreen; nicotinic acid metabolised to trigonelline, (cyanogenesis via tyrosine pathway); primary cell walls rich in xyloglucans and/or glucomannans, 25-30% pectin [Type I walls]; lignins derived from (some) sinapyl and particularly coniferyl alcohols, thus containing p-hydroxyphenyl and guaiacyl lignin units [so no Maüle reaction]; root xylem exarch, cork cambium deep seated; arbuscular mycorrhizae +; shoot apical meristem interface specific plasmodesmatal network; stem with vascular tissue around central pith [eustele], vascular bundles with interfascicular tissue, ectophloic, endodermis 0, xylem endarch; wood homoxylous, tracheids and rays alone, tracheid/tracheid pits circular, bordered; mature sieve tube/cell lacking functioning nucleus, sieve tube plastids with starch grains; phloem fibres +; stem cork cambium superficial; branches exogenous; leaves with single trace from vascular sympodium ["nodes 1:1"]; vascular bundles collateral [stem: phloem external; leaf: phloem abaxial]; stomata morphology?, pore opening in response to leaf hydration active, control by abscisic acid, metabolic regulation of water use efficiency, etc.; leaves with petiole and lamina, spiral, development basipetal, blade simple; axillary buds +, not associated with all leaves; prophylls two, lateral; plant heterosporous, sporangia borne on sporophylls; microsporophylls aggregated in indeterminate cones/strobili; true pollen +, grains mono[ana]sulcate, exine and intine homogeneous; ovules unitegmic, parietal tissue 2+ cells across, megaspore tetrad tetrahedral, only one megaspore develops, megasporangium indehiscent; male gametophyte development first endo- then exosporic, tube developing from distal end of grain, to ca 2 mm from receptive surface to egg, gametes two, developing after pollination, with cell walls, flagellae numerous; ovules increasing considerably in size between pollination and fertilization, female gametophyte endosporic, initially syncytial, walls then surrounding individual nuclei; seeds "large" [ca 8 mm3], but not much bigger than ovule, with morphological dormancy; embryo cellular ab initio, endoscopic, plane of first cleavage of zygote transverse, suspensor +, short-minute, embryo straight, shoot and root at opposite ends [allorrhizic], white, cotyledons 2; plastid transmission maternal; ycf2 gene in inverted repeat, two copies of LEAFY gene, PHY gene duplications [three - [BP [A/N + C/O]] - copies], nrDNA with 5.8S and 5S rDNA in separate clusters; mitochondrial nad1 intron 2 and coxIIi3 intron and trans-spliced introns present.
Lignans, O-methyl flavonols, dihydroflavonols, triterpenoid oleanane, non-hydrolysable tannins, quercetin and/or kaempferol +, apigenin and/or luteolin scattered, [cyanogenesis in ANITA grade?], S [syringyl] lignin units common [positive Maüle reaction - syringyl:guaiacyl ratio more than 2-2.5:1], and hemicelluloses as xyloglucans; root apical meristem intermediate-open; root vascular tissue oligarch [di- to pentarch], lateral roots arise opposite or immediately to the side of [when diarch] xylem poles; origin of epidermis with no clear pattern [probably from inner layer of root cap], trichoblasts [differentiated root hair-forming cells] 0, exodermis +; shoot apex with tunica-corpus construction, tunica 2-layered; reaction wood ?, associated gelatinous fibres [g-fibres] with innermost layer of secondary cell wall rich in cellulose and poor in lignin; starch grains simple; primary cell wall mostly with pectic polysaccharides, poor in mannans; tracheid:tracheid [end wall] plates with scalariform pitting, wood parenchyma +; sieve tubes enucleate, sieve plate with pores (0.1-)0.5-10< µm across, cytoplasm with P-proteins, cytoplasm not occluding pores of sieve plate, companion cell and sieve tube from same mother cell; sugar transport in phloem passive; nodes unilacunar [1:?]; stomata brachyparacytic [ends of subsidiary cells level with ends of pore], outer stomatal ledges producing vestibule, reduction in stomatal conductance to increasing CO2 concentration; lamina formed from the primordial leaf apex, margins toothed, development of venation acropetal, secondary veins pinnate, overall growth ± diffuse, venation hierarchical, fine venation reticulate, veins (1.7-)4.1(-5.7) mm/mm2, endings free; most/all leaves with axillary buds; flowers perfect, pedicellate, ± haplomorphic, parts spiral [esp. the A], free, numbers unstable, development in general centripetal; P not sharply differentiated, with a single trace, outer members not enclosing the rest of the bud, often smaller than inner members; A many, filament not sharply distinguished from anther, stout, broad, with a single trace, anther introrse, tetrasporangiate, sporangia in two groups of two [dithecal], ± embedded in the filament, with at least outer secondary parietal cells dividing, each theca dehiscing longitudinally, endothecium +, endothecial cells elongated at right angles to long axis of anther; tapetum glandular, cells binucleate; microspore mother cells in a block, microsporogenesis successive, walls developing by centripetal furrowing; pollen subspherical, tectum continuous or microperforate, ektexine columellate, endexine thin, compact, lamellate only in the apertural regions; nectary 0; G superior, free, several, ascidiate, with postgenital occlusion by secretion, stylulus short, hollow, cavity not lined by distinct epidermal layer, stigma ± decurrent, carinal, dry [not secretory]; ovules few [?1]/carpel, marginal, anatropous, bitegmic, micropyle endostomal, outer integument 2-3 cells across, often largely subdermal in origin, inner integument 2-3 cells across, often dermal in origin, parietal tissue 1-3 cells across [crassinucellate], nucellar cap?; megasporocyte single, hypodermal, megaspore tetrad linear, functional megaspore chalazal, lacking sporopollenin and cuticle; female gametophyte four-celled [one module, nucleus of egg cell sister to one of the polar nuclei]; ovule not increasing in size between pollination and fertilization; pollen binucleate at dispersal, male gametophyte trinucleate, germinating in less than 3 hours, pollination siphonogamous, tube elongated, growing between cells, growth rate 20-20,000 µm/hour, outer wall pectic, inner wall callose, with callose plugs, penetration of ovules via micropyle [porogamous], whole process takes ca 18 hours, distance to first ovule 1.1-2.1 mm; male gametes lacking cell walls, flagellae 0, double fertilization +, ovules aborting unless fertilized; P deciduous in fruit; seed exotestal, becoming much larger than ovule at time of fertilization; endosperm diploid, cellular [micropylar and chalazal domains develop differently, first division oblique, micropylar end initially with a single large cell, divisions uniseriate, chalazal cell smaller, divisions in several planes], copious, oily and/or proteinaceous; embryogenesis cellular; germination hypogeal, seedlings/young plants sympodial; dark reversal Pfr -> Pr; Arabidopsis-type telomeres [(TTTAGGG)n]; 2C genome size 1-8.2 pg [1 pg = 109 base pairs], whole genome duplication, ndhB gene 21 codons enlarged at the 5' end, single copy of LEAFY and RPB2 gene, knox genes extensively duplicated [A1-A4], AP1/FUL gene, paleo AP3 and PI genes [paralogous B-class genes] +, with "DEAER" motif, SEP3/LOFSEP and three copies of the PHY gene, [PHYB [PHYA + PHYC]].
[NYMPHAEALES [AUSTROBAILEYALES [[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]]]]]: wood fibres +; axial parenchyma diffuse or diffuse-in-aggregates; pollen monosulcate [anasulcate], tectum reticulate-perforate [here?]; ?genome duplication; "DEAER" motif in AP3 and PI genes lost, gaps in these genes.
[AUSTROBAILEYALES [[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]]]]: vessel elements with scalariform perforation plates in primary xylem; essential oils in specialized cells [lamina and P ± pellucid-punctate]; tension wood +; tectum reticulate; anther wall with outer secondary parietal cell layer dividing; carpels plicate; nucellar cap + [character lost where in eudicots?]; 12BP [4 amino acids] deletion in P1 gene.
[[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]]] / MESANGIOSPERMAE: benzylisoquinoline alkaloids +; polyacetate derived anthraquinones + [?level]; outer epidermal walls of root elongation zone with cellulose fibrils oriented transverse to root axis; P more or less whorled, 3-merous [possible positiion]; embryo sac bipolar, 8 nucleate, antipodal cells persisting; endosperm triploid; ?germination.
[MONOCOTS [CERATOPHYLLALES + EUDICOTS]]: (extra-floral nectaries +); (veins in lamina often 7-17 mm/mm2 or more [mean for eudicots 8.0]); (stamens opposite [two whorls of] P); (pollen tube growth fast).
MONOCOTYLEDONS / MONOCOTYLEDONEAE / LILIANAE Takhtajan
Plant herbaceous, perennial, rhizomatous, growth sympodial; non-hydrolyzable tannins [(ent-)epicatechin-4] +, neolignans, benzylisoquinoline alkaloids 0, hemicelluloses as xylans; root apical meristem?; root epidermis developed from outer layer of cortex; trichoblast in atrichoblast [larger cell]/trichoblast cell pair, the former further from apical meristem, in vertical files, or hypodermal cells dimorphic; endodermal cells with U-shaped thickenings; cork cambium in root [uncommon] superficial; root vascular tissue oligo- to polyarch, medullated, lateral roots arise opposite phloem poles; primary thickening meristem +; vascular bundles in stem scattered, (amphivasal), closed, vascular cambium 0; tension wood 0; vessel elements in root with scalariform and/or simple perforations; tracheids only in stems and leaves; sieve tube plastids with cuneate protein crystals alone; stomata parallel to the long axis of the leaf, in lines, brachyparacytic; prophyll single, adaxial; leaf base sheathing, sheath open, petiole 0, blade linear, main venation parallel, veins joining successively from the outside at the apex, endings not free, transverse veins +, unbranched, margins entire, Vorläuferspitze +, colleters [intravaginal squamules] +; inflorescence terminal, racemose; flowers 3-merous [6-merous to the pollinator?], polysymmetric, pentacyclic; P = T, each member with three traces, median member of outer whorl abaxial, aestivation open, members of whorls alternating, similar, [pseudomonocyclic, each providing a sector for the T tube when present]; stamens = and opposite each T member [primordia often associated, and/or A vascularized from tepal trace], anther and filament more or less sharply distinguished, anthers subbasifixed, endothecium from outer secondary parietal cell layer, inner secondary parietal cell layer dividing; G , with congenital intercarpellary fusion, opposite outer tepals [thus median member abaxial], placentation axile; ovule with outer integument often largely dermal in origin, parietal tissue 1 cell across; antipodal cells persistent, proliferating; fruit a loculicidal capsule; seed testal; endosperm with distinct nuclear and chalazal chambers, embryo long, cylindrical, cotyledon 1, apparently terminal, plumule apparently lateral; primary root unbranched, not very well developed, "adventitious" roots numerous, hypocotyl short, (collar rhizoids +), cotyledon with a closed sheath, unifacial [hyperphyllar], both assimilating and haustorial; no dark reversion Pfr -> Pr; duplication producing monocot LOFSEP and FUL3 genes [latter duplication of AP1/FUL gene], PHYE gene lost.
[ALISMATALES [PETROSAVIALES [[DIOSCOREALES + PANDANALES] [LILIALES [ASPARAGALES + COMMELINIDS]]]]]: ethereal oils 0; raphides + (druses 0); leaf blade vernation variants of supervolute-curved, (margins with teeth, teeth spiny); endothecium develops directly from undivided outer secondary parietal cells; tectum reticulate with finer sculpture at the ends of the grain, endexine 0; (septal nectaries + [intercarpellary fusion postgenital]).
[PETROSAVIALES [[DIOSCOREALES + PANDANALES] [LILIALES [ASPARAGALES + COMMELINIDS]]]]: cyanogenic glycosides uncommon; starch grains simple, amylophobic; leaf blade developing basipetally from hyperphyll/hypophyll junction [?level]; epidermis with bulliform cellls [?level]; stomata anomocytic, (cuticular waxes as parallel platelets); colleters 0.
[[DIOSCOREALES + PANDANALES] [LILIALES [ASPARAGALES + COMMELINIDS]]]: nucellar cap 0; endosperm nuclear [but variation in most orders].
[LILIALES [ASPARAGALES + COMMELINIDS]]: (inflorescence branches cymose).
[ASPARAGALES + COMMELINIDS]: style long.
Age. Thise node has been dated to 118-116 m.y.a (Bremer 2000b; Leebens-Mack et al. 2005). Other estimates are ca 122 m.y. (Janssen & Bremer 2004), (112-)107, 98(-93) m.y. (Wikström et al. 2001) and ca 133.1 and 118.6 (Magallón & Castillo 2009); estimates are (126-)122(-98) m.y. in Merckx et al. (2008a) and 116-94 m.y. in Mennes et al. (2013).
ASPARAGALES Link Main Tree.
Chelidonic acid +, steroidal saponins 0 [exact position where?]; (velamen +); (dimorphic root hypodermal cells +); anthers longer than wide; tapetal cells bi- to tetranuclear; microsporogenesis simultaneous; seeds exotestal, tegmen not persistent; endosperm helobial; mitochondrial sdh3 gene lost. - 14 families, 1122 genera, 26070 species.
Age. Crown group Asparagales may be ca 119 m.y.o. (Janssen & Bremer 2004), although Wikström et al. (2001: note topology) had suggested dates of 101-92 m.y.; Magallón and Castillo (2009) suggested ages of ca 125 and 112.6 (crown) m.y. and Bell et al. (2010) (114-)103, 92(-83) m.y.; estimates are (127-)119(-101) m.y. in Merckx et al. (2008a) and 96-93 m.y. in Mennes et al. (2013).
Note: Possible apomorphies are in bold. However, the actual level at which many of these features, particularly the more cryptic ones, should be assigned is unclear. This is partly because many characters show considerable homoplasy, in addition, basic information for all too many characters is very incomplete, frequently coming from taxa well embedded in the clade of interest and so making the position of any putative apomorphy uncertain. Then there is the not-so-trivial issue of how ancestral states are reconstructed...
Evolution. Divergence & Distribution. Asparagales may have the highest diversification rate in the monocots, about the same as Poales, but in both the rate is little over half that of Lamiales, the clade with the highest rate (Magallón & Castillo 2009); Magallón and Sanderson (2001) did not give estimates for the group. Within the clade, the diversity of Orchidaceae is indeed remarkable, but its sister taxon is all other Asparagales, somewhat less species-rich, perhaps, but a morphologically motley crew (see also below, under Orchidaceae). And sister to Asparagales are the commelinids... (see below).
Chemistry, Morphology, etc. Asparagales commonly have Arum-type arbuscular mycorrhizae, while in Liliales these mycorrhizae are commonly Paris-type (see F. A. Smith & Smith 1997). Storage mannans in the vegetative tissues are reported from Xanthorrhoeaceae-Asphodeloideae, Amaryllidaceae and Orchidaceae; they are uncommon elsewhere (Meier & Reid 1982). Mucilage polysaccharides in the roots of Asparagaceae-Asparagoideae may also have a storage role.
Three-trace tepals are found in Orchidaceae, Amaryllidaceae-Amaryllidoideae and -Agapanthoideae, Iridaceae, Xanthorrhoeaceae-Asphodeloideae (but not Kniphofia, Ashpodelus) and -Hemerocallidoideae, Asparagaceae-Agavoideae; one-trace tepals in Amaryllidaceae-Allioideae and Asparagaceae-Nolinoideae (but not Maianthemum stellatum), -Aphyllanthoideae, and -Asparagoideae. Asparagaceae-Scilloideae have tepals with both one and three traces, Urginea even having five traces in the outer whorls (see especially Chatin 1920). Where changes in microsporogenesis are to be placed on the tree is not clear. Furthermore, Rudall (2001a, see also 2002, 2003a) included an inferior ovary as a synapomorphy of the order, noting that in "higher" Asparagales there might be a reversal to superior ovaries that is associated with the presence of infralocular septal nectaries (as in Xanthorrhoea and Johnsonia (Xanthorrhoeaceae-Xanthorrhoeoideae and -Hemerocallidoideae). However, since superior ovaries are also scattered through the "lower" Asparagales, fitting ovary evolution to the tree is difficult; ovary position seems a much more flexible character here (and elsewhere) than it has generally been given credit for.
For flavonoids, see Williams et al. 1988), for ovule and seed, see Shamrov (1999a) and Oganezova (2000a, b), for cytology, see Tamura (1995), for cladodes, see Schlittler (1953b), for inflorescences, see Schlittler (1953a), for root morphology, see Kauff et al. (2000), for general morphology, see Rudall (2003a), for pollen of Japanese representatives, see Handa et al. (2001), for cytology and genome size, see Pires et al. (2006), and for the distribution of taxa with phytomelan and/or with baccate fruits, see Rasmussen et al. (2006).
Phylogeny. The tree here is based largely on the analyses in Chase et al. (2000a) and Fay et al. (2000: successive weighting). These studies differ little in detail, although the analysis of Fay et al. (2000) hardly suprisingly had more nodes in the core Asparagales with strong support. For the Amaryllidaceae + Agapanthaceae node, see Meerow et al. (2000b); relationships between Aphyllanthaceae, Themidaceae and Hyacinthaceae might be better represented as trichotomy (these families are now subsumed in a broadly-drawn Amaryllidaceae and Asparagaceae). The relationships in McPherson and Graham (2001) and D.-K. Kim et al. (2012) are largely congruent with the tree below, although their sampling is poorer and more geographically constrained.
Understanding the relationships between Boryaceae and Orchidaceae is critical. Boryaceae have been placed as sister to Orchidaceae (e.g. Chase et al. 1995a; McPherson & Graham 2001), although with rather weak support, while a [Boryaceae, Blandfordiaceae, etc.] clade were sister to other Asparagales in Janssen and Bremer (2004), while relationships above Orchidaceae were pectinate - [Orchidaceae [Ixoliriaceae [Tecophilaeaceae [Doryanthaceae + the rest]]]]; indeed, although although Janssen and Bremer (2004) did not place Orchidaceae sister to the rest of the order, in terms of time they placed it near the beginning of divergence within it. Orchidaceae were embedded in a paraphyletic Boryaceae-Hypoxidaceae clade (Li & Zhou: 2007), but again, with little support. In Wikström et al. (2001) Orchidaceae were sister to Hypoxidaceae. Seberg et al. (2012: mitochondrial and chloroplast data agreed only after removing edited mitochondrial sites) largely recovered the topology found by earlier workers; differences are mentioned below where they occur. In that study, mitochondrial data provided little support for the backbone of the tree.
Recent work suggests that Orchidaceae are sister to other Asparagales (e.g. 76% bootstrap support in Graham et al. 2006; about the same in Givnish et al. 2006b; stronger [96-99%] in Pires et al. 2006: good sampling, seven genes from two compartments). There was more or less strong support for the [Boryaceae, Blandfordiaceae et al.] clade in these analyses. While there is good support in Chase et al. (2006) for Orchidaceae being sister to all other Asparagales, Boryaceae were placed immediately above the Blandfordiaceae et al. clade, albeit with very little support. In some phylogenetic reconstructions of Hilu et al. (2003) Asparagales were paraphyletic, Orchidaceae being separate from the rest. Rudall (2003a: morphological data) suggested that there was a close relationship between Hypoxidaceae and Orchidaceae in particular, and also between Boryaceae and Blandfordiaceae and Iridaceae and Doryanthaceae. All in all, the topology [Orchidaceae [[Boryaceae, Blandfordiaceae et al.] [all other Asparagales]]], seems the best hypothesis. This affects the characterisation of Asparagales, since some characters previously considered to refer to the clade as a whole now move to the subbasal node in the tree (c.f. versions 6 and younger of this site).
Previous Relationships. Dahlgren et al. (1985) took important steps in reorganizing the relationships of "lily-like" monocots. They recognized two groups, Asparagales and Liliales, which were separable by features including patterning of the tepals and absence of phytomelan, both features of their Liliales. However, they still included Iridaceae and Orchidaceae in Liliales.
Includes Amaryllidaceae, Asparagaceae, Asteliaceae, Blandfordiaceae, Boryaceae, Doryanthaceae, Hypoxidaceae, Iridaceae, Ixioliriaceae, Lanariaceae, Orchidaceae, Tecophilaeaceae, Xanthorrhoeaceae, Xeronemataceae.
Synonymy: Asparagineae J. Presl, Asphodelineae Thorne & Reveal, Hyacinthineae Link, Iridineae Engler - Agavales Hutchinson, Alliales Berchtold & J. Presl, Amaryllidales Link, Apostasiales Martius, Asphodelales Doweld, Asteliales Dumortier, Gilliesiales Martius, Hypoxidales Martius, Iridales Rafinesque, Ixiales Lindley, Narcissales Dumortier, Orchidales Rafinesque, Tecophilaeales Reveal, Xanthorrhoeales Reveal & Doweld
ORCHIDACEAE Jussieu, nom. cons. Back to Asparagales
Mycorrhizal herbs, protocorms mycoheterotrophic, root hairs often lacking [?distribution]; flavone C-glycosides, flavonols +, chelidonic acid?; SiO2 bodies [stegmata] in leaf vascular bundle sheaths, these sheaths with fibres, (also fibre bundles in leaves); flowers rather weakly monosymmetric, resupinate; T free, median [abaxial] inner T differentiated [= labellum]; A 3, [median of outer whorl and laterals of inner whorl], basally adnate to style, anthers free; tapetal cells uninucleate; pollen with viscin; ovary inferior, septal nectaries 0, placentatation axile, placentae bilobed [?here], style solid [?all], stigmas commissural, wet; ovules ca 1500+/carpel, parietal tissue absent, funicle not vascularized; fruit dehiscing laterally by six valves, (indehiscent, ± baccate), T deciduous in fruit; seeds minute, dust-like; endosperm barely developing, none at maturity, embryo minute, undifferentiated, suspensor often haustorial (and branched); x = 7?
880[list]/22,075 - five subfamilies below. World-wide. [Photo - Flower]
Age. Crown group Orchidaceae have been dated to ca 111 m.y. (Janssen & Bremer 2004). The estimates of Ramírez et al. (2007: calibration by Miocene Goodyerinae pollinaria in amber, see esp. Supplementary Table) are somewhat younger at (90-)84-76(-72) m.y. (recalculated by Gustafsson et al. 2010 - (105-)80(-56) m.y.). Other crown group estimates include (105-)80-77(-56) m.y. (Gustafsson et al. 2010: BEAST; Bouetard et al. 2010: slightly older).
1. Apostasioideae Horaninov
Chemistry unknown; vessel elements in roots often with simple perforation plates, (vessels in stem +); stomata tetracytic; leaves spiral, vernation plicate; (flowers not resupinate - Apostasia); T develop from a ring primordium, apiculate, carinate, (labellum 0 - Apostasia); (A 2, staminode +/0 - Apostasia); pollen reticulate, (operculate); micropyle bistomal; (embryo sac bisporic, the spores chalazal, 8-celled [Allium type] - Neuwiedia); seeds entotestal, exotegmen sclerified [Neuwiedia], outer periclinal walls collapsing; n = 24.
2/16. Sri Lanka, N.E. India to N.E. Australia, Japan (map: from Pridgeon et al. 1999).
Age. Crown group Apostasioideae are (54-)49-45(-41) m.y.o. (Ramírez et al. 2007: recalculated by Gustafsson et al. (2010) as (66-)43(-23) m.y.) and (61-)41(-23) m.y. (Gustafsson et al. 2010).
Synonymy: Apostasiaceae Lindley, Neuwiediaceae Reveal & Hoogland
[Vanilloideae [Cypripedioideae [Orchidoideae + Epidendroideae]]]: C-glycosyl flavones, (saponins), 6-hydroxy flavonols +; (velamen +), (tilosomes +); vessel elements with scalariform perforation plates; leaves spiral or two-ranked; flowers strongly monosymmetric; (tepal nectaries +), abaxial outer tepal develops after inner whorl, labellum strongly differentiated; the style and A almost completely congenitally fused [= gynostemium], anthers to 2x as broad as long; pollen sticky; placentation parietal, stigma asymmetric; ovules not fully developed at pollination; fertilization may take some months; seeds dispersed before maturity of embryo; radicle 0.
2. Vanilloideae Szlachetko
Plant sympodial or monopodial, (echlorophyllous and/or viny); SiO2 bodies 0; stomata tetracytic; (venation reticulate); (calyculus +); T often carinate, (margins of labellum fused with column - some Vanilleae); A 1 [median member of outer whorl], staminodes 2 [lateral members of inner whorl], anther incumbent [bent forward] by massive expansion of the apical column/connective; "pollinia" +, soft, [not highly organized], viscidium 0, (pollen in tetrads; polyporate); (placentation axile), rostellum [ridge, part of median stigmatic lobe] +; (T persistent in fruit), (fruit baccate); seeds fusiform, crustose, exotestal [outer parietal wall well developed], tegmen persisting; endosperm to 16-nucleate; n = 9, 10, 12, 14-16, 18, etc.
15/180: Vanilla (100), Epistephium (12). Pantropical, esp. Asia; Australia, some N. America (map: from Pridgeon et al. 2003).
Age. Crown group Vanilloideae are (76-)71-65(-61) m.y.o. (Ramírez et al. 2007: recalculated by Gustafsson et al. 2010 as (79-)58(-39) m.y.) and (72-)57(-43) m.y. (Gustafsson et al. 2010).
Synonymy: Vanillaceae Lindley
[Cypripedioideae [Orchidoideae + Epidendroideae]]: ?
Age. The age of this clade is estimated at 37-26 m.y. by Wikström et al. (2001) and (69-)48, 42(-23) m.y. by Bell et al. (2010).
3. Cypripedioideae Kosteletzky
(Stomata paracytic); leaf vernation conduplicate or plicate; 2 abaxial T of outer whorl connate, labellum saccate; A 2, [lateral members of inner whorl], (pollinia +), staminode conspicuous, [median member of outer whorl]; tapetal cells binucleate; microsporogenesis successive?; pollen ± psilate (foveolate), operculate, (in tetrads); median stigma lobe largest; (micropyle bistomal); embryo sac bisporic [chalazal dyad], eight-celled [Allium-type]; (T persistent in fruit); n = 9 or more.
5/130: Paphiopedilum (62), Cypripedium (50). Mostly (warm) temperate N. Hemisphere, East Malesia and tropical South America (S. India) (map: from Hultén 1958; Pridgeon et al. 1999). [Photo - Flower]
Age. Crown group Cypripedoideae are (54-)49-44(-39)/(66-)43-41(-23) m.y.o. (Ramírez et al. 2007: recalculated by Gustafsson et al. 2010 as (49-)31(-17) m.y.) and (50-)33(-19) m.y. (Gustafsson et al. 2010). 37 ± 4; 34 ± 4 31
Synonymy: Cypripediaceae Lindley
[Orchidoideae + Epidendroideae]: floral primordium tranversely elliptic-oval; labellum initiated first; A 1, [median [abaxial] member of outer whorl], (staminodes 2 [from outer whorl]); microsporogenesis simultaneous [tetrads tetrahedral]; pollen in pollinia attached to sticky viscidium, pollinium/pollinarium stalk variously formed, from part of the anther [caudicula], epidermis of the rostellum [tegula] or apex of the rostellum [hamulus], pollen in tetrads (monads), porate or ulcerate; median [adaxial] carpel developed before the others, rostellum + [ridge, part of median stigmatic lobe, viscidium is also part of it]; T persistent in fruit; tegmen not persisting; endosperm not developing at all; n = 9 or more [19 common].
4. Orchidoideae Eaton
(Mycoheterotrophs +); plant sympodial;stem/root tuber common; (glucomannans +); SiO2 bodies 0; sclerenchyma in leaf [as fibre bundles or associated with vascular bundles] and stem rare; stomata anomocytic; leaves usu. spiral, soft, herbaceous, deciduous; anther erect (incumbent), apex acute, staminodes reduced; pollinia soft/sectile, (hamulus [pollinium stalk from modified apical part of rostellum] +); n = 12-24 [x = 7?].
208/3755: Habenaria (600), Caladenia (376), Platanthera (200), Pterostylis (200), Disa (175), Cynorkis (125), Orchis (125), Corybas (120), Goodyera (80-100), Satyrium (90), Disperis (85), Prasophyllum (80), Cyclopogon (75), Pelexia (75), Peristylus (75), Zeuxine (70), Diuris (55), Goodyera (55), Holothrix (55), Cheirostylis (50), Dactylorhiza (50), Thelymitra (50). World-wide, esp. temperate (map: from Pridgeon et al. 2001, 2003; distribution in N. Asia and N. North America unclear).
Age. Crown group Orchidioideae are (63-)58-52(-48) m.y.o. (Ramírez et al. 2007: recalculated by Gustafsson et al. 2010 as (67-)50(-34) m.y.) and (64-)53(-42) m.y. (Gustafsson et al. 2010).
Synonymy: Neottiaceae Horaninow, Limodoraceae Horaninow, Liparidaceae Vines, Ophrydaceae Vines
5. Epidendroideae Kosteletzky
(Mycoheterotrophs +); epiphytes common, plant often then sympodial, (plant without shoots or leaves [Vandeae]); (pyrrolizidine alkaloids +); (SiO2 bodies 0); velamen + (0), (roots with pneumathodes); stomata often para- or tetracytic; stems thick; leaves usu. 2-ranked, vernation conduplicate (plicate), articulated with sheathing base (not), (unifacial, terete, or isobifacial, equitant); anther incumbent [bent forward by column elongation, or by very early anther bending (vandoids)], (strongly convex), with beak, operculate; pollinia clavate, hard (soft/sectile), [pollinium stalk from apical part of median stigma lobe], pollen inaperturate[?]; (inside of carpel wall with hairs); (cotyledon visible); n = 5+.
650/18000: Bulbophyllum (2035), Epidendrum (1500), Dendrobium (1400), Pleurothallis (1000), Lepanthes (>800), Stelis (700-900 s.str., 1100 s.l.), Oncidium (520), Masdevallia (410), Liparis (320), Malaxis (300), Maxillaria (ca 300), Crepidium (280), Dendrochilum (265), Calanthe (260), Acianthera (200), Coelogyne (200), Specklinia (200), Angraecum (200), Eulophia (200), Phreatia (190), Oberonia (175), Taeniophyllum (170), Phreatia (160), Pinalia (160), Telipogon (160), Octomeria (150), Gomesa (125), Cyrtochilum (120), Dracula (120), Encyclia (120), Dichaea (110), Trichosalpinx (110), Ceratostylis (100), Catasetum (100), Elleanthus (100), Glomera (100), Prostheacea (100), Sobralia (100), Camaridium (80), Brassia (75), Platystela (75), Brachionidium (65), Appendicula (60), Callostylis (60), Comparettia (60), Neottia (60), Nervilia (60), Notylia (60), Podochilus (60), Scaphyglottis (60), Sophronitis (60), Ornithidium (55), Fernandezia (50), Lepanthopsis (50), Maxillariella (50), Restrepia (50), Rodriguesia (50). More or less world-wide, but most diverse in the tropics; rather poorly developed in Australia (map: from Pridgeon et al. 2005).
Age. Crown group Epidendroideae are estimated at (67-)59-51(-44) m.y.o. (Ramírez et al. 2007: recalculated by Gustafsson et al. 2010 as (60-)44(-29) m.y. and (62-)49(-38) m.y. (Gustafsson et al. 2010).
Synonymy: Pycnanthaceae Ravenna
Evolution. Divergence & Distribution. We know little about the origin and biogeography of the family (see also Chase 2003). Ramírez et al. (2007) suggest that the subfamilies had diverged by the end of the Cretaceous, ca 65 m.y.a., or perhaps slightly later in the early Palaeocene, and that orchid radiation has been a Tertiary phenomenon; dates suggested by Gustafsson et al. (2010) are somewhat younger, major diversification perhaps occurring during the cooler period at the end of the Eocene and into the Oligocene, rather that during the thermal maximum earlier in the Eocene (c.f. Ramírez et al. 2007).
Bouetard et al. (2010) estimated that crown group Vanilla started to diversify ca 34 m.y.a., at least three instances of long distance dispersal being needed to explain its present distribution.
Gravendeel et al. (2004 and references; see also Peakall 2007) list the numerous hypotheses that have been advanced to explain the diversity of Orchidaceae; these include pollinator specialization, niche partitioning, habitat fragmentation, wide dispersal of the seeds, etc. Interestingly, there is surprisingly low genetic differentiation between orchid populations, despite the possibility for long-distance transport of the minute seeds with resultant founder effects (Phillips et al. 2012). Orchid diversity is most often attributed to the nature of the association of the plant with its pollinator, as is discussed below. Normally neither orchids nor pollinating insects are diverse on oceanic islands, but angraecoid orchids are surprisingly diverse on the Mascarene islands, and Reunion in particular also has a diverse insect fauna (Micheneau et al. 2008). Some of the distinctive features of the family seem to be biologically connected. Thus pollinia ensure the fertilization of numerous ovules; the minute seeds that result are usually devoid of endosperm or differentiated embryo, and the obligate myco-heterotrophy of the young plant may compensate for the absence of seed reserves (Johnson & Edwards 2000 in part; Eriksson & Kainulainen 2011).
Endress (2011a) thought that the inferior ovary in Asparagales might be a key innovation, although where this feature should be placed on the tree is unclear - perhaps here is one place. The presence of pollinia is another feature that he mentioned; this is probably best placed as a synapomorphy of the [Orchidoideae + Epidendroideae] clade. But complicating any story about diversification, Orchidaceae are sister to the rest of Asparagales, florally and vegetatively very diverse and with some 6,850 species (c.f. Sargent 2004: Orchidaceae compared with Hypoxidaceae - only 100-220 species), and Asparagales as a whole are sister to commelinids, with some 22,750 species. Within Orchidaceae, clades of 16, 180, and 130 species are successively sister to the rest of the family, so suggesting a rather more complicated story (see also in part Smith et al. 2011). Shifts to the epiphytic habit and the associated adoption of CAM photosynthesis are as likely to have been important in the diversification of the family as anything else (Gravendeel et al. 2004). Finally, it is worth remembering that much of the floral variation in Orchidaceae is at one level a series of intricate combinations of a rather limited theme. Most species have a single anther, a labellum, a very similar gynoecium, etc., although the variations of the pollinaria and particularly the protean elaborations of the labellum are truly remarkable.
Plant-Animal Interactions. Members of Orchidaceae are not often eaten by butterfly caterpillars (Janz & Nylin 1998) or by insect herbivores in general, although Riodininae-Riodininae larvae may be found on them (Hall 2003 and references). Pyrrolizidine alkaloids are known from genera like Phalaenopsis and Pleurothallis...
Pollination Biology & Seed Dispersal.
Orchid flowers may be notably long-lived (months!), although some last only for a single day. Flowers are commonly resupinate, the ovary being twisted about 180°, the labellum ending up in the abaxial position (Ernst & Arditti 1994; Yam et al. 2009 for reviews). However, the amount of resupination often varies within a plant, especially when the inflorescence is arching; here all flowers of the inflorescence are oriented so that their labellum is in the same position with respect to gravity, with the ovary sometimes being twisted 360° (as in Angraecum, etc.) or not at all. Fischer et al. (2007) discuss the variety of ways - of which twisting of the pedicel is but one of the mechanisms involved - that flowers in the speciose Bulbophyllum present themselves in the Malagasy region. In genera like Calopogon the flowers are never resupinate, and all flowers on the erect inflorescence show "normal" monocot orientation, the labellum being adaxial. In the dioecious Catasetum resupination varies between staminate (resupinate) and carpellate (not resupinate) flowers (see below).
The most conspicuous element of floral variation is the labellum, a highly-differentiated member of the inner whorl of tepals, which shows a truly remarkable diversity of form and colour (Rudall & Bateman 2002); duplication of genes may be involved (Mondragón-Palomino & Theißen 2008). The spatial relationships of the labellum and column in particular force the pollinator to approach the flower in a particular way, and in general, pollinaria are very precisely placed on the pollinator, closely related orchid species differing in exactly where their pollinaria are placed (e.g. Maad & Nilsson 2004). After the pollinarium is attached, the pollinia may move, so bringing them into the proper position for pollination (for pollinia and polinaria, see Rasmussen 1982; Freudenstein & Rasmussen 1996, 1997; Johnson and Edwards 2000; Pacini & Hesse 2002; Freudenstein et al. 2002; Selbyana 29: 1-86. 2008).
A final distinctive feature of many orchid flowers is that the ovules are usually not fully developed - and may not even be recognizable - at anthesis, and fertilization is often delayed relative to pollination, as in Cypripedium. The time between pollination and fertilization ranges from four days to ten months (in Vanda), the normal time being one week to six months (Wirth & Withner 1959, Yeung & Law 1997; also Sogo & Tobe 2005, 2006d for references: ?Situation in Apostasioideae). Even after fertilization, it may be a month before embryo development begins, as in Sarcanthinae (Wirth & Withner 1959 for references).
Orchid pollination is discussed here first emphasizing the rewards, then the pollinator, with some other issues mentioned at the end.
REWARDS. The plesiomorphic condition for the family may be to lack nectar (Jersáková et al. 2006); all told, perhaps 8,000 species of orchids lack nectar. Cozzolino and Widmer (2005; see also Schiestl 2005) suggested that orchid diversification is associated with the deceptive pollination mechanisms that are so prevalent in the family; about one third of the species - estimates range from 6,500 to 10,000 - are pollinated in this way (Schiestl 2005, 2010 for reviews, the latter brief; Schlüter & Schiestl 2008: molecular mechanisms; Peakall 2009: deceit and speciation; Schaefer & Ruxton 2010: exploitation of perceptual biases of the pollinator by the plant; Gaskett 2011: the pollinator's point of view in sexual deception; Xu et al. 2012; Pemberton 2013: deceit in Cypripedioideae). Deceit comes in various guises, from sexual deceit, where the orchid mimics a female insect and pollen exchange occurs during pseudocopulation (e.g. Ophrys below), to food deceit, pollen apparently being available for removal (Pogonieae), to domicile deceit, as in Serapias (Orchideae: Bellusci et al. 2008 for a phylogeny) and Cypripedium (Pemberton 2013), which apparently attract pollinators by mimicking a nest hole. In the speciose African Disa (Orchidoideae), there have been several transitions from deceit to nectar rewards, and loss of nectar, and independent gains and losses of spurs - all without having much of an effect on diversification rates (Johnson et al. 2003). Note that there are several cases where flowers that offer rewards have been derived from those that do not (Cozzolino et al. 2001; Cozzolino & Widmer 2005; Smithson 2009; Johnson 2013).
Flowers of the European Ophrys (Orchidoideae-Orchideae) are well known for their mimicry of bees and wasps (e.g. Kullenberg 1961; Paulus 2006). They have a distinctive labellum and produce chemicals that are very similar to insect pheromones; alkenes (hydrocarbons with at least one double bond) are involved in the chemical component in this mimicry (e.g. Stökl et al. 2009; Ayasse et al. 2011; Xu et al. 2012). Morphology and scent together enable the Ophrys flower to mimic female insects (Cortis et al. 2009 and references), pollination occurring as male bees and wasps in particular attempt to copulate with the flowers (Kullenberg 1961). Barriers to crossing - floral form and scent again - act before pollination; no deleterious effects of hybridization, which occurs in the wild, have been noted (Xu et al. 2011). Scent chemicals are common in related genera as well (Schiestl & Cozzolino 2008), and Ophrys is part of a larger clade in which food deception seems to be the basic condition (Inda et al. 2012). However, there is currently much discussion about species limits in Ophrys, with estimates of species numbers ranging from 16 to 215, the former perhaps being closer to "reality" (Vereecken et al. 2011; Bateman et al. 2006a, 2011a; Devey et al. 2008); whether "species formation in Ophrys always proceeds with the aquisition of a new species of pollinating males" (Pauluis 2006, p. 315) or not will depend on this debate.
In the Australian Chiloglottis (Orchidoideae-Diuridae) there is a fair degree of congruence between the phylogenies of the orchids and the deceived wasps (Mant et al. 2002, 2005; see also Weston et al. 2011). Again, understanding species limits is critical; here there seem to be a number of cryptic species (Griffiths et al. 2011). Caladenia (also Diuridae) is another example (Jones et al. 2001). In such sexually-deceptive orchids both morphological and genetic differences between species or even genera are slight (Schiesl 2005 and references; Mant et al. 2005; see also below).
Deceit pollination (pollen mimicry) involving bees also occurs in Vanilloideae-Pogonieae where it characterises a clade that includes temperate species; the production of rewards may be derived here (c.f. Pansarin et al. 2012). A number of species of Oncidiinae have flowers like those of oil-producing Malpighiaceae. They have radiating, clawed, yellow or purple "petals" that are similar in both overal floral shape and in colour, bee-UV-green, to flowers of Malpighiaceae, and they may be part of a Batesian mimicry system, both groups being visited by bees like Centris, etc. - the orchids have no reward for the bee (Reis et al. 2007; Neubig et al. 2012a; esp. Papadopulos et al. 2013). The mimicry unit of the orchid is formed largely by the labellum, with the column being equivalent to the banner petal of the malpig. M. P. Powell (in Neubig et al. 2012a) has estimated that such mimicry may have evolved at least 14 times within Oncidiinae, indeed, it may be both lost and regained (Papadopulos et al. 2013). Some Oncidiinae may also mimic Calceolaria, another oil flower (Neubig et al. 2012a). Deceit pollination also occurs in the large genus Epidendrum (Pinheiro & Cozzolino 2013).
Many orchids do have rewards for the pollinator. Pollen alone is collected from flowers of Apostasioideae, and even from some Vanilloideae (Pansarin et al. 2012). Nectar flowers are quite common (Bernadello et al. 2007 and references). The flowers of Satyrium are not resupinate and have twin nectar spurs (Johnson et al. 2011a), while Angraecum, Habenaria, etc., also have nectar spurs. The nectaries vary in position (Davies et al. 2005) although they are never septal. In a number of species of Maxillaria hairs on the labellum contain protein and perhaps also starch and function as pseudopollen, so rewarding the pollinator (Davies et al. 2000; Davies 2009), while resins and oils are also quite common rewards.
For a summary of what little is known of oil flowers in Orchidaceae, which have evolved probably at least a dozen times, eight times in Maxillarieae alone, see Renner and Schaefer (2010). Orchids with oil as a reward may show convergence with the flowers of other oil-pollinated plants. Some 70 spp of Oncidiinae have elaiophores, sometimes on the labellum, and the oil produced is identical to that produced in the flowers of Malpighiaceae , and their flowers are otherwise very similar to those of Malpighiaceae (see above; Reis et al. 2007); some kind of Müllerian mimicry system may be operating here (Papadopulos et al. 2013). Pollination of some South African Orchidoideae-Coryciinae (e.g. Disperis) is by oil-collecting bees; the flowers have paired, pouch- or spur-like structures like those of another local oil plant, Diascia (Scrophulariaceae: Pauw 2006). Moreover, the distinctive lip-like appendage that was a defining feature of the old Corycinae (Waterman et al. 2009) seems to have evolved in parallel, although relationships are not entirely clear. The South African Huttonaea, perhaps immediately unrelated, also has oil flowers (Steiner 2010); Steiner et al. (2011) analyzed scent composition of many southern African oil-secreting Diseae. Resins as a reward have evolved several times in Maxillaria and its relatives, but other rewards occur there, and there are even some species that have flowers that may mimic the presence of resin rewards (Whitten et al. 2007; Davies & Stpiczynska 2012). See also Chase et al. (2009) and Steiner (2010) for oil flowers.
POLLINATORS. Turning now to different pollinator groups, fly pollination is common (Christensen 1994), especially in Epidendroideae, for example in the very speciose and largely Old World Bulbophyllum. Dark, purplish-coloured flowers with carrion scent, a mobile labellum, and often dangling hairs of various kinds attract flies. A number of taxa have sweet, fruity scents and lighter-coloured flowers and are pollinated by fruit flies - which may also be commercially important pests (Tan 2008 and references, see also Texeira et al. 2004; Fischer et al. 2007 for resupination there). In the New World, pollination during pseudocopulation with fungus gnats (dipterans, often Sciaridae) has been reported in the large genus Lepanthes (Blanco & Barboza 2005). How this system might function is unclear since there is no obvious connection between the morphology of the orchid flower and that of the fungus gnat (Singer 2011). Be that as it may, fly pollination of one sort or another, sometimes with with nectar reward, but usually sapro- or mycomyophily, is likely to predominate in the some 4,000+ species of Pleurothallidinae, to which Lepanthes belongs (Borba et al. 2011). Pollination by Drosophila and Scatophaga is also known in Cypripedium (Li et al. 2012).
Butterfly, moth and even bird pollination are also well known in the family. Angraecum sesquipedale, from Madagascar, is a classic example. There the spur is about 30 cm long, and the pollinator for long remained unknown, although Darwin (1862) suggested that some moth with a proboscis that long would be found. Indeed, Xanthopus morgani praedicta, with a proboscis length of about 25 cm, was subsequently discovered (Nilsson et al. 1987; Nilsson 1988: Arditti et al. 2012; Micheneau et al. 2010: pollination in angraecoid orchids). For spurs, nectariferous and otherwise, in Orchidoideae-Orchidinae, see Bell et al. (2009), and for the great floral and pollinator diversification in some of its genera, including Disa, see Johnson et al. (1998, 2013) and Bytebier et al. (2007). For paired spurs in Satyrium, see Johnson et al. (2011a), and for spurs in the largely Australian Diurideae, see the summary in Weston et al. (2011: also various kinds of mimicry, nectar evolved [and lost] many times, etc.). Spurs are common in Vandeae, which includes Angraecum; for spurs in Aeridinae, see Topik et al. (2005).
It has been estimated that perhaps 60% of Orchidaceae are pollinated by bees (Schoonhoven et al. 2005), whether deceived or not (see also above). Williams (1982) discussed the general importance of male euglossine bees in particular in the pollination of neotropical Epidendroideae (see also Roubik 1988). Male bees pollinate as they search for fragrances that they collect and store in their hind tibial pockets, and the some 190 species of bees pollinate perhaps up to 25% of tropical American Orchidaceae, hence their common name, orchid bees. About 700 species of orchids have fragrances that attract male bees, some 85% of all plants with such fragrances (Ramírez 2009). Euglossine pollination occurs especially in orchids growing at lower altitudes, and anywhere from 700-2,000 species may be so pollinated (Cameron 2004 and references; Zimmermann et al. 2009 - Photo: bee pollinators). Euglossines also pollinate many Zingiberales, Gesneriaceae, Lecythidaceae, etc., which are also visited for nectar, pollen, and resins. All told orchid bees pollinate thousands of species of plants (Ramírez et al. 2011).
Although the bees are effective pollinators, the relationships between orchids and euglossine bees are non-specific on both sides (Cameron 2004). Importantly, crown-group euglossines can be dated to 42-27 m.y.a., with especially rapid diversification 20-15 m.y.a. (Ramírez et al. 2010) or (35-)28(-21) m.y.a. (Cardinal & Danforth 2011). (Stem-group euglossines are Cretaceous in age - e.g. Grimaldi & Engler 2005.) The orchids these bees pollinate speciated somewhat later, 30-15 m.y.a. (Ramírez et al. 2011), and belong to at least three immediately unrelated clades. Given the timing of evolution of the two, and the behaviour of the orchids and that of the bees in particular, simple insect-orchid co-speciation is not an explanation for the diversification of the orchids. Indeed, at least most of the compounds that the bees pick up from the orchids are usually found elsewhere, too, and many other fragrances are acquired from other sources. Orchids may be exquisitely adapted to individual pollinators whose sensory biases they may exploit (Schiestl 2010), but individual species of orchid bees, for example, may pollinate several species of orchids - not to mention many other species of plants (Ramírez et al. 2011). Closely related and sympatric species of Euglossa did show greater disparity in the fragrances they preferred than might be expected, the distinctive fragrance signals collected from orchid flowers perhaps being involved in pre-mating isolation in the bees; overall, however, the most dominant compounds in the fragrances were highly homoplasious (Zimmermann et al. 2009).
The pollination of Catasetinae, Catasetum in particular, by male euglossine bees is well known (Darwin 1862; Chase & Hills 1992 for a phylogeny; Gerlach 2013). Catasetum has remarkable flowers, even for an orchid: Not only does resupination differ between staminate (resupinate) and carpellate (non-resupinate) flowers, but there are many other striking differences, especially in labellum morphology, between the two; indeed, staminate and carpellate specimens were once put in separate genera, Myanthus and Monachanthus respectively. The attachment of the pollinaria on the bees is by an explosive mechanism, which startles the insect (Nicholson et al. 2008). Romero and Nelson (1986) suggested that as a result the bees subsequently avoided male flowers - hence the very different morphologies of the female flowers "The battered polliantor will remember the negative ezperience with the male flower" (Gerlach 2012: p. 39), which, however, are very similar between the species.
GENERAL. The connection between the orchid-pollinator relationship and orchid diversification is a matter of active discussion - but see the caveats above about estimating diversification. Reproduction in orchids may often be pollinator-limited (Tremblay et al. 2005), with few flowers on an inflorescence producing seeds, however, the production of huge numbers of seeds by each fruit may compensate for this - orchids "specialize in chance" (Pérez-Hérnandez et al. 2011). Recent studies suggest that when pollinators visit orchid flowers in the course of deceptive pollination or to pick up scent rewards - specialized pollination mechanisms - pollinator specifity is greater and species richness is greater than when pollinators visit for nectar (Schiestl & Schlüter 2009; Xu et al. 2011; Schiestl 2012: sister-group comparisons; see also Dressler 1968; Scopece et al. 2010a for pollination efficiency). Thus deceit pollination may under certain situations increase outcrossing and speciation, the latter perhaps because of the specificity of the pheromones produced by the plants (Jersáková et al. 2006; see also Ledford 2007).
The presence of well-developed and effective premating barriers in Orchidaceae may have obviated any pressure for the selection of postmating barriers. As a result, artificial crosses are often easy to make, and hybrids may have three or more genera in their parentage, although how these will look when generic boundaries are redrawn is unclear. Thus many genera in Laeliinae can be crossed artificially (van den Berg et al. 2000, 2009). Interestingly, it has been suggested (based on work on European orchids) that in those orchids with generalized food-deceptive mating mechanisms, barriers to crossing may be postzygotic, whereas those that practice sexual deception have prezygotic reproductive barriers, and introgression is more likely in this latter situation (Cozzolino & Scopece 2008).
Tremblay et al. (2005) reviewed the evolutionary consequences of the diversity of the pollination mechanisms of Orchidaceae and the remarkable variation shown by their flowers. Orchid diversification is often explained in terms of the close association between pollinators and individual species of orchids, but recent work suggests very strongly that strict co-speciation should not always be assumed (Ramírez et al. 2011), and factors other than floral variation may have contributed to the diversification of Orchidaceae - see "Vegetative Variation" and "Ecology & Physiology" below. The generation of diversity by floral specialization may be relatively uncommon in flowering plants in general, although perhaps occurring here (Armbruster & Muchhala 2009).
For summaries of pollination in Orchidaceae, see van der Cingel (1995, 2001), Endress (1994b), Biol. J. Linnean Soc. 173: 713-773. 2013, etc. - and of course the classic study by Darwin (1862a) is still worth reading (see also Yam et al. 2009). For a general discussion on floral evolution in the family, with an emphasis on terata and homeosis s.l., see Rudall and Bateman (2002).
Most orchids produce immense numbers of minute dust seeds, up to 4,000,000 seeds per fruit or 74,000,000 seeds per plant, the seeds being as little as 150 µm long or less (Arditti & Ghani 2000; Yam et al. 2009). Orchidaceae have particularly small seeds when compared with their immediate relatives (Moles et al. 2005a), and the seeds usually lack endosperm and a differentiated embryo. Much of the seed, small as it is, is in fact empty space, and the seeds are well suited for wind dispersal (Arditti & Ghani 2000). Although Arditti (1967) did suggest that a few species had recognizable cotyledons, the species mentioned are not basal in the tree. The subterrananean myco-heterotroph Rhizanthella has baccate fruits with large, crustose seeds (Weston et al. 2011).
Ecology & Physiology.
Fungi and Orchids.
The obligate association of orchids and saprotrophic fungi is central to understanding the physiology of the orchid plant. The fungal hyphae can form intracellular pelotons, complex coils of hyphae, inside the plant cells, and these may be digested by the host; the consensus is that orchid mycorrhizae are basically modified ectomycorrhizae (Smith & Read 1997). Establishment of this association is integral to the successful establishment of the seedling, and the sometimes rather protracted obligate myco-heterotrophic phase of the young plant probably compensates for the absence of seed reserves (Johnson & Edwards 2000 in part; Eriksson & Kainulainen 2011; Leake & Cameron 2012), however, a few orchids can germinate in the absence of a fungus. Sugars and nitrogen move from the fungus to the orchid (Zimmer et al. 2007), and the initial association results in a protocorm (Peterson et al. 1998). Which came first, the dust seeds or the myco-heterotrophic association, is almost a chicken-or-egg question.
Details of the fungus-orchid association were until recently unclear in Apostasioideae, although it was known that the fungus Tulasnella was involved, a genus also found in Cypripedium, etc. (Kristiansen et al. 2004; see also Yukawa et al. 2009; Roche et al. 2010). The fungus is found in stomatiferous root tubercules, and these may make the plant better able to deal with wet conditions (Stern & Warcup 1994). Interestingly, seeds of Apostasioideae are rather larger than those of other orchids.
Most adult orchids are autotropic, fixing all their own carbon, some are mixotropic, obtaining some carbon from the fungus, while myco-heterotrophic orchids lack chlorophyll and are dependent on the fungus for all carbon (and nitrogen); for a review, see Dearnalay et al. (2012). More or less echlorophyllous myco-heterotrophs (holomycotrophs), have evolved some 30 or more times in Orchidaceae, and some 210 species are mycoheterotrophic (Molvray et al. 2000; Merckx & Freudenstein 2010; Freudenstein & Barrett 2010). They are most common in ground-dwelling Epidendroideae, where about 1 in 10 species is a myco-heterotroph (Freudenstein & Barrett 2010). The Australian Rhizanthella (Orchidoideae-Diuridae) is a subterranean holomycotroph, the flowers even opening underground. It has the smallest chloroplast genome of any land plant, about 59,000 BP, but there is still a core group of functioning genes (Delannoy et al. 2011).
Tulasnella is a saprotrophic fungus, and although associated with a number of adult orchids, these are autotrophic (Summer et al. 2012; Ogura-Tsujita et al. 2012). In Cymbidium (Epidendroideae), the evolution of mixotrophy and then mycoheterotrophy was associated with the establishment of associations between the orchids and ectomycorrhizal fungi (Ogura-Tsujita et al. 2012). In Corallorhiza (Epidendroideae) several species of Russula form both an ectomycorrhizal association with adjacent trees and an endomycorrhizal association with the orchid (Taylor & Bruns 1999); the tree is the ultimate source of the carbon. Indirect associations with trees are known from other than myco-heterotrophs (e.g. Bidartondo & Read 2008). Bi- or unidirectional movement of carbon has been detected even in chlorophyllous orchids (Cameron et al. 2008; Hynson et al. 2009a). Non-mycorrhizal but lignin-decaying fungi like Mycena (Mycenaceae) are also involved in such associations; Mycena supports the fully myco-heterotrophic Gastrodia confusa in the manner to which it has become accustomed (Ogura-Tsujita et al. 2009: see references for more examples).
The Epiphytic Habitat.
Epiphytes are particularly common in Orchidaceae-Epidendroideae; all told, about 70% of all Orchidaceae, some 18,800 species, are epiphytes. Indeed, there are more species of epiphytic orchids than of all other vascular epiphytes combined, orchids comprising ca 70% of epiphytic flowering plants (Benzing 1983; Zotz 2013). Indeed, speciation in Orchidaceae may increase in epiphytic clades, e.g. in Epidendroideae-Bulbophyllinae (Gravendeel et al. 2004). Twig epiphytes, concentrated in a clade of the New World Epidendroideae-Cymbidieae-Oncidiinae, are particularly distinctive. They grow on twigs less than 2.5 cm in diameter in very exposed and high light conditions, and their seed coats have little grapnels, perhaps aiding in their attachment to the twigs (Chase & Pippen 1988). The plants are very small and may mature within a year (Chase 1987; Chase and Palmer 1997; Neubig et al. 2012a); indeed, many of these epiphytes are exposed to light on germination, rather than starting off with a slow-growing subterranean mycotrophic phase (Leake & Cameron 2012). Their leaves are isobifacial and are arranged like a small fan (the psygmoid habit) and the plants have no pseudobulbs. All in all, they look like very young plants of other Oncidiinae and are more or less paedomorphic (Chase 1987; Neubig et al. 2012a for references; Chase et al. 2005 for genome size).
In the epiphytic habitat orchids have to deal with periodic drought and lack of nutrients (Gravendeel et al. 2004, see also Motomura et al. 2008), rather as in dry terrestrial habitats. Succulence is appropriate for a habitat in which water availability is uncertain (see also Figueroa et al. 2008); terrestrial orchids have thinner leaves. Nyffeler and Eggli (2010b) estimate that some 50+ genera and 2,200 species, especially epiphytic species - or perhaps double that number - are succulents. It is not surprising that many epiphytic Epidendroideae, perhaps some 7,000 species, are likely to have crassulacean acid metabolism (CAM) photosynthesis (Winter & Smith 1996b); variants of CAM photosynthesis such as CAM-cycling are also common (see Cameron et al. 2008 for Oncidiinae). (The actual number of taxa involved is unclear. In a survey of 1,002 Costa Rican orchids, only some 10% of Vanilloideae and Epidendroideae were found to show signs of strong CAM, perhaps 30% more had weak CAM; CAM was not found in Orchidoideae and Cypripedioideae [Silvera et al. 2010a].) CAM has evolved perhaps ten times in Orchidaceae, and has also reversed to C3 photosynthesis; adoption of CAM is predominantly by epiphytic Epidendroideae growing at low altitudes and drier conditions (Silvera et al. 2009; Kerbauy et al. 2012) and has been linked to the Tertiary radiation of that subfamily (Silvera et al. 2009).
The photosynthetic pathway in root and stem may be different (Martin et al. 2010), indeed, photosynthesis in orchid roots is poorly understood. Studies on cauline pseudobulbs, common in epiphytic orchids, suggest that they may sometimes carry out CAM even although they lack stomata: CAM occurs in Bulbophyllum minutissimum, however, the pseudobulb there is a modified leaf, even if lacks a blade, so one presumes there are stomata, and CAM also occurs in the roots of the leafless Campylocentrum tyrridion, which lack stomata (Kerbauy et al. 2012 and references).
Mycorrhizal associations are less common in epiphytic plants (e.g. Janos 1993; Desirò et al. 2013). However, Sebacinales and Tulasnellales have been found as ectomycorrhizal associates in neotropical epiphytic orchids, species of Tulasnellales, at least, colonizing more than one species of orchid (Kottke et al. 2008; see also Martos et al. 2012; Gowland et al. 2013).
Bacterial/Fungal Associations. Orchids characteristically have a very close association between basidiomycete and some ascomycete fungi. Rhizoctonia (= Ceratobasidium) is a common anamorph or form genus that encompasses a multitude of sins (Dearnalay et al 2012) - Russulaceae, Tuber, and Sebacinales-B (found with autotrophic orchids, and in the same clade, but different from those on Ericaceae - Setaro et al. 2012) and -A (with mixotrophic and myco-heterotrophic orchids) are all involved here. The commonest families are Tulasnellaceae (perhaps the most important group - Martos et al. 2012), Ceratobasidiaceae and Sebacinaceae (see Currah et al. 1997 and Yukawa et al. 2009 for lists of fungi; Otero et al. 2002; Roy & Selosse 2009; Weiß et al. 2009), but some neotropical Epidendroideae have Atractiellomycetes (in the same clade as Puccinia) as mycobionts (Kottke et al. 2010). The fungi associated with the plant as it germinates may be quite different from those associated with the adult plant (Hashimoto et al. 2012 and refs.). Although Rinaldi et al. (2008) thought that only 10 species of fungi might be involved, the number is far greater, even in a relatively small area (e.g. Martos et al. 2012). Martos et al. (2012) discussed the literature on the phylogenetic signal of orchid and fungus.
Yukawa et al. (2009) suggested that the basidiomycete Cantherellales may have been the fungus group first associated with Orchidaceae. At least some of the fungi are probably saprophytes living on decaying plant material that can also form close relationships with orchids (Ogura-Tsujita et al. 2009; Yukawa et al. 2009). The specificity of the mycorrhizal association is unlikely to be connected with the diversification of the family (c.f. Otero & Flanagan 2006). The relationship between fungus and orchid is by no means one-on-one (e.g. Martos et al. 2012: identification method important; Leake & Cameron 2012) and can even seem pretty random, at least in the pezizalean associates of Epipactis studied by Tesitelova et al. (2012). Individual North American clades in the myco-heterotroph Corallorhiza striata complex are associated with different sets of the fungus Tomentella (Thelephoraceae: Barrett et al. 2010), Roche et al. (2010) studied the specificity of the basidiomycete Tulasnella-Chiloglottis association (see also Otero et al. 2011), while Nurfadilah et al. (2013) found that fungi varied in their ability to utilize nutrients in phosphorous-poor West Australian soils, suggesting that this might help explain the commonness of different species of orchids there.
Recent work on orchids growing on Reunion suggests that the nature of the mycorrhizal network in epiphytic and terrestrial species differs, with only 10 of the 95 fungal species (taxonomic units) recorded found in species from both groups. Furthermore, most of the species obligately restricted to one of the groups as well those occuring in both were found on only one or two of the orchid species (Martos et al. 2012). Differences between the species of fungi found in the two habitats, or in features of the orchids that affect colonization by the fungi, may both explain this striking pattern (Leake & Cameron 2012).
For endophytic fungi, see Bayman and Otero (2006). Very little is known about them, and the one fungus may even be pathogen, endophyte, and mycorrhizal symbiont.
Vegetative Variation. Orchidaceae show considerable diversity in habit and other vegetative features despite their generally modest size. Some Sobralieae are slender, cane-like plants up to about 10 m tall, while the geophytic habit is quite common in Orchidoideae. Tatarenko (2007) summarized the extensive vegetative variation of temperate orchids, i.e. especially Orchidoideae.
The vernation of orchid leaves varies. The blade may be quite thin to thick, bifacial, isobifacial (equitant) or unifacial (terete), and the leaf bases are sometimes massively swollen. Leaves may be spirally arranged to 2-ranked. Some ground- and shade-dwelling species have distinctively-coloured and -patterned leaves that makes them particularly attractive to horticulturists. Extrafloral nectaries are scattered, being found on the stems opposite the leaves in Vanilla, at the bases of the pedicels in Cymbidium, etc.
Stems, leaves or even roots may be succulent (Nyffeler and Eggli 2010b; also Figueroa et al. 2008). Individual leaf blades of Bulbophyllum may be some and weigh. Some epiphytic Epidendroideae-Vandeae either lack photosynthetic leaves or have very deciduous leaves. The vegetative plant then consists largely of photosynthetic roots. These roots may be stout (ca 5 mm across) and terete, as in Dendrophylax, while the aptly named Taeniophyllum has distinctively flattened roots (e.g. Carlsward et al. 2006b). All told, over 200 species, all epiphytes, are involved, and Freudenstein (2012) estimated that there had been at least 20 independent losses of leaves in Epidendroideae.
The roots of these plants, and those of many other Epidendroideae, appear to lack root hairs, although they may develop on the side of the root facing the substrate (von Guttenberg 1968); the root hairs ("rhizoids") are sometimes described as being branched (Rasmussen 1999). Orchid roots in general are often rather stout; a velamen, which has spiral thickenings on the cell walls, is well developed around the outside (von Guttenberg 1968). Pneumathodes are common in Epidendroideae, and leafless Vandeae have aeration units in their roots. These latter consist of distinctive exodermal cells, a space beneath, and a pair of thin-walled cortical cells; such aeration units are also found in related leafy Vandeae (Benzing et al. 1983; Carlsward et al. 2006a, b). How carbon dioxide and water flux are controlled in leafless epiphytes is unclear, especially because there are no stomata in the roots, although the aeration units may be stomata analogues (Benzing et al. 1983; Cockburn et al. 1985). Roots of New World epiphytic Epidendroideae in particular have distinctive tilosomes, cells of the innermost layer of the velamen that are adjacent to the passage cells of the exodermis and that have complex often lignified excrescences developing from the wall (Pridgeon et al. 1983). However, such cells are also found in ground-dwelling Orchidoideae-Spiranthinae (Figueroa et al. 2008) and their exact function is unclear.
The End. Returning to the question, Why are there so many orchids?, Orchidaceae are distinctive in several ways, of which their flowers and fruits are just two. Vegetative variation, more or less associated with habit and habitat, is almost equally striking. Futhermore, Waterman et al. (2011) distinguish between speciation and coexistence in orchids, and note that shifts in details of pollination (placement of pollinaria, pollinating insect) occur with speciation, although associations with different fungi may promote the co-occurrence of immediately unrelated orchid species. No one feature of itself is likely to be responsible for orchid diversification.
Genes & Genomes. There is much variation in chromosome number and size. Thus Apostasioideae and Orchidoideae have small chromosomes, while larger chromosomes occur in Cypripedioideae and Vanilloideae; Felix and Guerra (2010) survey chromosome number variation in Epidendroideae. For genome size, see Leitch et al. (2009) and Jersáková et al. (2013); it varies 168-fold.
matK in Apostasioideae may be in transition from a possibly functional gene to a pseudogene; in the other members of the family examined (but the sampling is poor) it is a pseudogene (Kocyan et al. 2004).
Chemistry, Morphology, etc. Orchidaceae seem to be the only clade outside the commelinids with SiO2 bodies (e.g. ), but I am not sure if they are an apomorphy for the family; they are certainly sometimes lost. For the anatomy of Apostasioideae, see Stern et al. (1993); the subfamily is poorly known.
Monosymmetry of the flower in many, but not all orchids - and in Hypoxidaceae and Doryanthaceae - is evident even in the earliest primordia (Kurzweil & Kocyan 2002 and references). A few Orchidaceae have more or less polysymmetric flowers, and in Telipogon (Epidendroideae - Oncidiineae) a polysymmetric perianth becomes evident only late in development (Pabón-Mora & González 2008). Duttke et al. (2012) discuss the remarkable terata to be found in Neofinetia falcata (Vandeae: Aeridinae) that have been accumulated in Japan over the last 350 years. For floral development and the expression of B-, C- and D-class genes in particular in Dendrobium, see Y. Xu et al. (2006); genes of all three classes are expressed in the column. The sequence of organ initiation varies considerably within the family (Pabón-Mora & González 2008). Thus Apostasioideae and Cypripedioideae have simultaneous initiation of members of the inner tepal whorl, the plesiomorphic condition for Asparagales (Kocyan & Endress 2001a); have Vanilloideae been studied? At least some Orchidaceae have placentoids (Weberling 1989).
Anthers of some species appear to be bisporangiate in early development (Freudenstein & Rasmussen 1996). Prutch and Schill (2000) discuss variation in the morphology and ultrastructure of the stigma; variation seems to be at about the subfamilial level. Although the seeds are generally minute and the testa cells have thin walls, Selenipedium (Cypripedioideae) has a hard, dark testa, although apparently it lacks phytomelan.
For general information, see Schlechter (1992, 1996, 2003), Dressler (1993), and Szlachetko (1995); for accounts of Apostasioideae, see de Vogel (1969) and Pridgeon et al. (1999), for Cypripedioideae, Pridgeon et al. (1999), Vanilloideae, Pridgeon et al. (2003), for Orchidoideae, Pridgeon et al. (2001b, 2003), and for Epidendroideae, Pridgeon et al. (2005, 2009); for terrestrial orchids, see Rasmussen (1999), and for an illustrated generic account, see Alrich and Higgins (2008). Anatomy: Epidendroideae, see Stern et al. (2004), Stern and Carlsward (2006, 2009), and Morris et al. (1996: Dendrobium), for Orchidoideae, see Stern (1997a, b), Stern et al. (1993b), and for Apostasioideae, Stern et al. (1993a); see also Pridgeon et al. (1983: tilosomes), Porembski and Barthlott (1988: velamen), Prychid et al. (2004: SiO2 bodies), Mayer et al. (2011: colleters, uncommon), and Aybeke (2012: esp. rhizome and roots of Orchidoideae and Epidendroideae. For reticulate venation in Vanilloideae, see Cameron and Dickison (1998).
See also Hirmer (1920: floral morphology), Swamy (1948a: floral vasculature, 1949: endosperm development, embryology), Rao (1973: floral anatomy), Wirth and Withner (1959: embryology and development), van der Pijl and Dodson (1966: pollination), Newton and Williams (1978: Cypripedioideae, Apostasioideae pollen), Schill and Pfeiffer (1977: pollen, general), Li et al. (2012: pollinia in Cypripedioidae), Clements (1995: not read, embryology, etc.), Endress (1994b: floral morphology), Yeung and Law (1997: ovules and embryo sac), Kurzweil (2000), Molvray et al. (2000), Cameron and Chase (2000), Szlachetko and Rutkowski (2000) and Szlachetko and Margonska (2002), both gynostemium, Kristiansen et al. (2001), Johansen and Frederiksen (2002: flowers), Cameron (2002), Kurzweil (esp. 1987, 1993), Kocyan and Endress (2001a) and Kurzweil and Kocyan (2002), all floral development, Yeung (2005: embryogeny), Rasmussen and Johansen (2006: fruits), and Bell et al. (2009: nectar spurs in Orchidoideae).
Phylogeny. Cameron (2007) provided a summary of phylogenetic studies on the family. There may still be some uncertainty over the position of Cypripedioideae (e.g. Cameron 2004). In some analyses they grouped (albeit weakly) with Vanilloideae (Freudenstein & Chase 2001) or were sister to Orchidaceae minus Apostasioideae, which might make sense if thinking about androecial evolution (alone Cameron et al. 1999: one gene, successive weighting). However, they are often placed sister to Orchidaceae minus Apostasioideae and Vanilloideae (e.g. Kocyan et al. 2004; Cameron & Chase 2000; Cameron 2002, 2005b, 2006: two genes, in a basal trichotomy with atp alone; Górniak et al. 2010: nuclear gene Xdh). This latter hypothesis, followed here, suggests that the monandrous condition may have evolved twice (see also Freudenstein et al. 2002, 2004). There are also suggestions that Codonorchis is sister to [Epidendroideae + Orchidoideae] (e.g. Clements et al. 2002) or basal in Orchidoideae (Cameron 2006). It may need to be kept separate if in the former position (it has whorled leaves - see Cameron 2006; c.f. Jones et al. 2002).
For a phylogeny of Apostasioideae, see Kocyan et al. (2004).
Relationships within Vanilloideae are becoming fairly well resolved (Cameron 2004, 2009; Cameron & Molina 2006; Pansarin et al. 2008). Included are Pogoniinae (Erythrorchis, a mycoheterotroph, is here), Vanillinae, and Galeolinae and Lecanorchidinae (both mycoheterotrophs); Bouetard et al. (2010) provide a phylogeny for Vanilla. Pansarin et al. (2012) evaluated the phylogeny of Pogonieae; Pogoniopsis is to be placed in Epidendroideae.
For relationships in Cypripedioideae, including also a morphological survey, see Albert (1994). Li et al. (2011) found morphology sometimes to have misled over relationships in Cypripedium; for a phylogeny of Paphiopedilum, see Chochai et al. (2012).
Orchidoideae include the erstwhile Spiranthoideae which have incumbent anthers (as in Epidendroideae) with apical rostellar tisssue. Relationships within Orchidoideae are becoming fairly well resolved (e.g. Cameron 2004); see also Inda et al. (2010: cox1 intron). For relationships in Orchideae, see Inda et al. (2012); New World species of Habenaria (Orchideae-Habenariinae) are monophyletic (Batista et al. 2013). Clemens et al. (2002) clarify relationships of Diuridae, a few of which are to be placed in Epidendroideae; for Codonorchis, see above. Disa is especially diverse in the Cape Region (see Bytebeier et al. 2007, 2008); for a phylogeny of Satyrium, see van der Niet and Linder (2008); it has diversified in the Fynbos region (Verboom et al. 2009). Prescottiinae s.l. have diversified at very high altitudes - up to 4,900 m - in the Andes (Álvarez-Molina & Cameron 2009). For information about relationships in the speciose Caladenia, see Australian J. Bot. 57(4). 2009, for a study of Diuridae, Clements et al. (2002), of Pterostylis and relatives, see Clements et al. (2011), of the African Disa (Disinae), see Bytebier et al. (2007), and of the American Chloraeinae, see Cisternas et al. (2012). For the phylogeny of Cranichidae, see Salazar et al. (2003: monophyly and characters of subtribes, 2011a: comments on Spiranthinae), while Górniak et al. (2006) discuss relationships in Spiranthinae and Salazar et al. (2011a) examined relationships around Dichromanthus et al.; there adaptation to bird pollination has occurred in parallel, confusing generic limits.
For general phylogenetic relationships in Epidendroideae, see van den Berg (2005) and Górniak et al. (2010). Support for branching along the spine of Epidendroideae is not strong (e.g. Cameron et al. 1997; Pridgeon et al. 2001b; Cameron 2004). Palmorchis is sister to Neottieae, the combined clade being sister to all other Epidendroideae (Rothacker & Freudenstein 2006). Xiang et al. (2012; see also Freudenstein 2012) found at least three more clades, including Sobralia and Elleanthus, Nervilia and Tropidia respectively, to be successively sister to the rest at the base of the "higher Epidendroideae". These "basal" clades tend to lack articulated leaves, they have no velamen, and their pollinia are sectile (Pridgeon et al. 2005); if so, this will affect identification of apomorphies for the subfamily. Malaxis and Liparis may not be monophyletic, but are closely intertwined; it is likely that they are secondarily terrestrial. For a summary of what is known about Epidendrum, see Pinheiro and Cozzolino (2013).
Within Dendrobieae, the speciose Dendrobium is turning out to be polyphyletic (Yukawa & Uehara 1996: vegtatively variable, florally perhaps less so; Yukawa et al. 1993, 1996, 2000; Clements 2003 and earlier work: revisionary studies and phylogeny). The largely Old World and also very diverse Bulbophyllum is less studied, but the few (ca 60) New World species form a clade sister to the African taxa, the genus evolving in the general Southeast Asian region (Gravendeel et al. 2004; Smidt et al. 2011); Fischer et al. (2007) studied the Malagasy species. For a major study of Pleurothallidinae, see Pridgeon et al. (2001b); Pleurothallis is also not monophyletic (Chiron et al. 2012: focus on Brazilian species). Abele et al. (2005) and Matuszkiewicz and Tukallo (2006) discussed the phylogeny of Masdevallia, while Karremans et al. (2012) looked at relationships in Stelis, which has sometimes been extended to include "a few hundred" species of Pleurothallis. Russell et al. (2010) discuss phylogeny in the widely-distributed Polystachya (Vandeae: monopodial), where there is some correlation of polyploidy with wide species distributions. Topik et al. (2005) investigated relationships in Aeridinae; characters conventionally used to establish relationships showed little congruence with the tree they obtained (see also Hidayat et al. 2005). For angraecoid orchids in general (Angraecineae), see Stewart et al. (2006). For phylogenetic relationships in Laeliinae, see van den Berg et al. (2000), for diversification in Coelogyninae, see Gravendeel et al. (2005), for studies in Maxillarieae, see Whitten et al. (2000), Williams and Whitten (2003), Sitko et al. (2006), Arévalo and Cameron (2013), and especially Whitten et al. (2007: Maxillaria to be restricted, generic realignments needed) and in Oncidiinae, Williams et al. (2001a, b, 2005), in Cymbidieae, Whitten et al. (2005), Cieślicka (2006: Eulophia), Neubig et al. (2008: Dichaea, Zygopetalinae), and Chase (1987), Chase and Palmer (1997), Williams et al. (2001), Chase et al. (2009) and especially Neubig et al. (2012a) all focusing on Oncidiinae and the polyphyletic Oncidium, in Epidendreae (Kulak et al. 2006), and in Sobralieae, Neubig et al. (2011).
The recently described monotypic Pycnanthaceae from northwestern Argentina may be somewhere near Orchidaceae, as Ravenna (2011) suggested, even teratological, but the description is inadequate (and the measurement units in the description not always correct). The leaf sheaths are described as being closed, the flowers have a labellum, there are supposed to be three stamens with extrorse anthers, and the placentation is parietal. The type specimen looks like Malaxis (M. Chase, pers. comm.) and that is where it is to be placed (Nicola 2012).
Classification. Chase et al. (2003) provide a higher-level phylogenetic classification for the family, while Govaerts et al. (2003) is a provisional checklist of the family (see also World Checklist of Monocots). For useful accounts of Apostasioideae, see Pridgeon et al. (1999), Cypripedioideae, Pridgeon et al. (1999), Vanilloideae, Pridgeon et al. (2003), Orchidoideae, Pridgeon et al. (2001b, 2003), and Epidendroideae, Pridgeon et al. (2005, 2009).
Generic limits in the family are in the middle of a major overhaul to make them consistent with molecular findings, many of which have implications for clade/generic circumscriptions. It is now clear that there is widespread homoplasy in floral features (e.g. Waterman et al. 2009; Chase et al. 2009 and references), and in the past the importance of floral differences in separating genera has been over-emphasized. Szlachetko et al. (2005 and references) give a statement of the "floral" position, maintaining that variation in column form, etc., yields taxonomically important characters (see also Szlachetko 1995; Rutkowski et al. 2008). However, clade limits suggested by molecular studies and generic limits suggested by floral features alone by no means always agree (Kocyan et al. 2008 and references). The features characterising the erstwhile broadly-delimited and polyphyletic Oncidium - mimicry of oil flowers of Malpighiaceae, whether or not the orchid also offers oil as a reward - is a good example of this (Williams et al. 2001; Neubig et al. 2008; Stpiczynaska & Davies 2008; Chase et al. 2009; esp. Neubig et al. 2012a), similarly, in Aeridinae there is also probably widespread parallelism in floral characters used to delimit genera (Hidayat et al. 2005; Salazar et al. 2011a, b for other examples). It is not that floral morphology is taxonomically useless, but as elsewhere, undue reliance on it will lead us seriously astray if our interest is in understanding phylogeny. In some Epidendroideae vegetative variation may correlate better with clades evident in molecular phylogenies (e.g. Cameron 2005a), although anatomical variation by itself may suggest little major phylogenetic structure (Stern et al. 2004; Stern & Carlsward 2006). For generic limits in Maxillariinae, c.f. Whitten et al. (2007) and Szlachetko et al. (2012) and in Habenariinae, see Batista et al. (2013 and references).
There have been extensive discussions about generic limits in European Orchidinae (Tyteca & Klein 2008, 2009; Bateman 2009; Scopece et al. 2010b). In an attempt to make generic limits there more objective, Scopece et al. (2010b) found that clade membership correlated well with post-zygotic reproductive isolation (embryo death). A phylogeny-based classification in which this and other evidence was incorporated could be defended on more explicit grounds, and this would allow morphologically distinctive taxa previously segregated as separate genera be incorporated into their proper clades (Scopece et al. 2010b). This approach is somewhat reminiscent of that of Danser (1929), and although perhaps useful in Orchidaceae - but it is going to be interesting to see how widely it can be applied even here, and what the taxonomic consequences are - it may be inapplicable to other angiosperms with different breeding behaviours.
Such disagreements reflect fundamental differences in classificatory philosophies and differing beliefs in the ability of morphology when used alone alone to disclose relationships. However, even having a phylogeny and agreeing over basic taxonomic philosophies does not mean that there will be automatic agreement about generic limits. Clements (2006 and references) suggested a wholesale pulverization and reorganization of Dendrobium and its relatives. The species numbers given above do not reflect this, and Burke et al. (2008), Janes and Duretto (2010), Schuitema and Adams (2011), and Schuitema (2012) suggest that a broader circumscription of the genus would be preferable; species limits are also at issue here (Adams 2011: focus on Australia). Jones and Clements (2002a, esp. 2002b) divide Pterostylis; since the monophyly of Pterostylis s.l. was confirmed, the division is perhaps questionable (if one likes broadly-drawn generic limits), and indeed Janes and Duretto (2010) and Jones et al. (2010) suggest returning to the old circumscription of the genus. However, Clements et al. (2011) note that there are nine or so identifiable groups around here... Jones et al. (2001) also dismember the monophyletic Caladenia and Clements et al. (2002) divide a monophyletic Corybas, as do Jones et al. (2002 - also much else). Such cases simply reflect conflicting preferences for narrow or broad genus limits, so they are something of a pain. In any event, in Australia, the result of nomenclatural changes made for these and other reasons is that about 45% of the species and subspecies in the entire orchid flora of some species have acquired new generic names in the brief period between 2000 and mid-2009 (Hopper 2009) - surely, this is Taxonomic Progress. Finally, Reveal (2012) came up with an earlier name for Epidendroideae (10 versus 58,500 hits - Google search iv.2012), but it will perhaps go the way of an earlier name that was found for Chloridoideae - oblivion. One can but hope for sense.
For an infrageneric classification of Vanilla, see Soto Arenas and Cribb (2010), and for an account of Anacamptis, Orchis, etc., see Kretzschmar et al. (2007). For a reclassification of Pleurothallidinae, see Pridgeon and Chase (2001); Pleurothallis was not monophyletic - but c.f. Karremans et al. (2012). This is a huge group, and sampling is still relatively very poor. There is some controversy about generic limits in the Masdevallia area, c.f. Luer (2006) and Pridgeon (2007), and reclassification of Maxillarieae is likely (Whitten et al. 2007); Blanco et al. (2007) made many new combinations.
[[Boryaceae et al.] [[Ixoliriaceae + Tecophilaeaceae] [Doryanthaceae [Iridaceae [Xeronemaceae [Xanthorrhoeaceae [Amaryllidaceae + Asparagaceae]]]]]]]: (stem fructans +); (cuticular waxes as platelets transversely arranged in parallel series); (T ± connate); (A inserted on T tube); seeds exotestal, (phytomelan +).
Chemistry, Morphology, etc. For the distribution of fructose oligosaccharides, see Pollard (1982) and Meier and Reid (1982). Although recorded there only for some Hypoxidaceae in the [Boryaceae [Blandfordiaceae [Lanariaceae [Asteliaceae + Hypoxidaceae]]]] clade, and not for some of the smaller families elsewhere in Asparagales, fructans seem to be widespread in this part of the tree; they were not recorded from Orchidaceae.
[Boryaceae [Blandfordiaceae [Lanariaceae [Asteliaceae + Hypoxidaceae]]]]: septal nectaries external; ovules with hypostase; embryo sac with chalazal constriction, antipodal cells persistent.
Age. This node can be dated to m.y. (Janssen & Bremer 2004: but c.f. topology).
There are many dates for clades in this area in both Janssen and Bremer (2004) and Wikström et al. (2001), but the topologies there differ from that above; if relationships change, some ages may be of use.
Chemistry, Morphology, etc. For some information, see Kocyan and Birch (2011); there is extensive homoplasy in this little clade, so exactly where features like "septal nectaries external" are to be placed is unclear.
Phylogeny. Relationships between Milligania and Lanaria and Blandfordia were suggested by Bayer et al. (1998a). Kocyan and Birch (2011: all genera studied) found that Lanariaceae, Asteliaceae and Hypoxidaceae formed a tritomy, while Seberg et al. (2012) found that jackknife support for the clade was poor, and that Asteliaceae and Lanariaceae reversed their positions, i.e. to [Asteliaceae [Lanariaceae + Hypoxidaceae]], and relationships were also scrambled in Janssen and Bremer (2004) and Wikström et al. (2001).
BORYACEAE M. W. Chase, Rudall & Conran Back to Asparagales
Plant xeromorphic; aerial stems +, rhizome short; roots mycorrhizal; endodermis much thickened; bundles with lateral phloem; leaves spiral, base sheathing; inflorescence scapose, involucrate, raceme or spike; T tube short; A adnate to tube [not Alania]; anthers (centrifixed), little longer than wide; septal nectaries external; ovules many/carpel, micropyle bistomal, parietal tissue 1 cell across; T persistent in fruit; (seed papillate - Borya); endosperm helobial, without starch, embryo short, ovoid; n = 11, 14; seedling?
2[list]/12. Australia, scattered (map: see Brittan et al. 1987). [Photo - Borya Habit © M. Fagg]
Age. Crown group Boryaceae are dated to 54 m.y. (Janssen & Bremer 2004).
Ecology & Physiology. Borya has tuberculate roots that may have the coil-forming Rhizoctonia fungus is them (c.f. Orchidaceae); the plant is arborescent and dessication-tolerant (e.g. Barthlott 2006) and has vessels with almost simple perforation plates in the stem (Carlquist 2012a).
Chemistry, Morphology, etc. The pedicels of Alania have several bracteoles.
Additional information is taken from Dahlgren et al. (1985) and Conran (1998), both general, and Conran and Temby (2000: floral morphology).
Previous Relationships. Genera of Boryaceae have often been included in Anthericaceae (= Asparagaceae-Agavoideae), as by Takhtajan (1997).
[Blandfordiaceae [Lanariaceae [Asteliaceae + Hypoxidaceae]]]: nucellar cap ca 2 cells across.
Age. The age of this clade is estimated at (98-)81, 74(-56) m.y. by Bell et al. (2010: note topology).
Phylogeny. An at most moderately well-supported - if consistently appearing - group (Rudall et al. 1998a; Chase et al. 2000a; Fay et al. 2000; Davis et al. 2004 - Lanariaceae not included; Graham et al. 2006; Chase et al. 2006; etc.).
Chemistry, Morphology, etc. See Conran and Temby (2000) for general information, especially about ovules.
BLANDFORDIACEAE R. Dahlgren & Clifford Back to Asparagales
Rhizome short; chemistry?; velamen +; raphides 0; plant glabrous; leaves two-ranked, vernation flat-curved, midrib prominent, sheath?; inflorescence a raceme; pedicels articulated; T large, tubular; (A adnate below middle of tube), anthers latrorse, centrifixed; pollen trichotomosulcate; G stipitate, septal nectaries on outside of ovary; style short, stigma ± punctate, dry; ovules many/carpel, outer integument 3-4 cells across, hypostase +; capsule septicidal; exotesta papillate; embryo short; n = 17, 27; cotyledon photosynthetic.
1[list]/4. E. Australia (map: see Brittan et al. 1987). [Photo - Blandfordia Flower © B. Walters]
Chemistry, Morphology, etc. Information is taken from Clifford and Conran (1998: general), Di Fulvio and Cave (1965) and Prakash and Ramsey (2000: both embryology) and Kocyan and Endress (2001b: some floral morphology.
Previous Relationships. Rudall (2003a) suggested that there was a close morphological relationship between Boryaceae and Blandfordiaceae.
[Lanariaceae [Asteliaceae + Hypoxidaceae]]: hairs multicellular, often branched; stomata paracytic; blade with distinct midrib; G ± inferior, septal nactaries internal; ovule with bistomal micropyle, micropyle zig-zag.
LANARIACEAE R. Dahlgren Back to Asparagales
Plant with vertical rhizome; biflavones +; raphides 0 (styloids +); indumentum dendritic; leaves two-ranked to spiral, sheath ?closed; inflorescence branched; T connate half-way; A adnate in mouth; G ± inferior, style long, stigma punctate; ovules 2/carpel, apotropous, outer integument 5-7 cells across, parietal tissue ca 3 cells across, obturator +; capsule type?; seed 1; exotesta palisade, other cells rounded, tegmen persists, develops at micropyle; endosperm initially with starch; n = 18; seedling?
1[list]/1: Lanaria plumosa. Cape Province, South Africa. [Photo - Habit] [Photo - Habit.]
Chemistry, Morphology, etc. Information is taken from De Vos (1963 - embryology), Dora and Edwards (1991 - chemistry) and Rudall (1998 - general).
[Asteliaceae + Hypoxidaceae]: plants rosette-forming or caespitose; flavonols +; mucilage canals +; endosperm thin-walled; cotyledon not photosynthetic, ligule long.
ASTELIACEAE Dumortier Back to Asparagales
Plant ± rhizomatous; saponins +; indumentum lepidote-stellate; leaves spiral, base sheathing or not; plant dioecious (flowers perfect), inflorescence branched raceme or spike, inflorescence bracts large; flowers rather small, T connate basally (free); A adnate to base of T/free; (nectaries on outside of ovary); (G subinferior; placentation parietal), intra-ovarian trichomes +, style branched or not (short), stigmas dry; ovules few to many/carpel, ?nucellar cap; fruit a berry; (seed with mucilaginous hairs), endosperm oily, no hemicellulose; n = 8, 30, ?35, chromosomes 4-6 µm long; seedling primary root well developed.
1[list]/36. New Zealand to New Guinea, Pacific Islands E. to Hawaii, Chile, the Mascarenes (map: see van Steenis & van Balgooy 1966; Brittan et al. 1987). [Photos - Milligania & Astelia Flowers © C. Howells - Australian Plants Society, Tasmania.]
Age. Crown-group Asteliaceae are dated to ca 92 m.y. (Janssen & Bremer 2004). Birch et al. (2012) date the crown group to (76-)55.4(36.0) my (Bayesian; ca 69.6 m.y. penalized likehood).
Evolution. Divergence & Distribution. For the biogeography of the family see Birch et al. (2008, 2011, esp. 2012); there has been extensive long-distance dispersal. Given the current ideas of relationships in the family (see below), character evolution in it will repay investigation.
Chemistry, Morphology, etc. Carlquist (2012a) suggested that vessels were practically absent, except perhaps in the roots - although this might depend on the technique used to prepare the material.
For additional information, see Prakash and Ramsey (2000: embryology), and Bayer et al. (1998a: general) for information.
Phylogeny. The phylogeny of the family has been clarified by Birch et al. (2009); Milligania, with loculical capsular fruits, a semi-inferior ovary and no intra-ovarian trichomes, perfect flowers, etc., and often considered rather different from other Asteliaceae, seems to be embedded in Astelia, as do the other small genera previously recognized in the family (Birch et al. 2008, esp. 2009). Birch et al. (2012) found that [Neoastelia + Milligania] were sister to the rest of the family; Astelia is to include Collospermum.
HYPOXIDACEAE R. Brown, nom. cons. Back to Asparagales
Stem ± cormose to rhizomatous, leaf bases persisting, contractile roots common; saponins 0; velamen +, dimorphic root hypodermis 0; stomata (tetracytic), with oblique or parallel cell divisions; leaves 3-ranked, (vernation conduplicate-)plicate (conduplicate-flat), (unifacial), sheaths also closed; inflorescence various, scapose, axis flattened; (flowers 2-merous); T free to tubular; (A inserted towards base), (many), (3, plus 3 staminodes adnate to style [= gynostemium] - Pauridia), (extrorse), (basi- or centrifixed, sagittate); tapetum amoeboid, microsporogenesis successive [tetrads tetragonal]; (pollen to trisulcate, inaperturate); ovary inferior, (apical beak +), septal nectaries 0, (placentation parietal - Empodium), stigmas commissural, ± 3-radiate, dry or wet; ovules few to many/carpel, apotropous, (outer integument to 4 cells across), (nucellar cap 0), (parietal tissue 0); (embryo sac bisporic, 8-celled [Allium type]); fruit dehiscing laterally and loculicidally, circumscissile), indehiscent, or baccate; seeds globose, smooth to spiny, (strophiole +); exotesta palisade or not, (endotegmen persistent), raphe prominent; endosperm nuclear to helobial, (perisperm +, slight); n = 6-9, 11, chromosomes 2-5 µm long; embryo short, ± undifferentiated.
7-9[list]/100-220: Hypoxis (50-100). Seasonal tropics, esp. southern Africa (temperate) (map: see Fl. N. Am. 26: 2002; Australia's Virtual Herbarium xi.2012). [Photo - Inflorescence, Flower.]
Age. Crown group Hypoxidaceae have been dated to ca 78 m.y.a. (Janssen & Bremer 2004).
Evolution. Pollination Biology & Seed Dispersal. Pollen is the main reward, and flies of various kinds, beetles and bees seem to be the pollinators (Kocyan et al. 2011 for a summary). At least some species of Hypoxis are apomictic (Nordal 1998).
Chemistry, Morphology, etc. Kocyan (2007) found that some flowers of Curculigo racemosa were polyandrous, however, the stamens were not fasciculate. The staminodes of Pauridia that are adnate to the style rather surprisingly appear to represent the outer androecial whorl - and they are responsible for reports of a 6-lobed stigma in the family. The rostrum, a narrowed, beak-like apical part of the ovary, appears to have evolved more than once, but its function is uncertain; the beak may also be formed by the connate tepals.
There is controversy over the tapetum type in the family and in the numbers of nuclei in the cells, and whether or not there is a velamen in the root. The ovules have a parietal cell, so are not tenuinucellate [?incorrect - not in the literature I have read]. The endosperm is reported as being nuclear or helobial; if the former, then the antipodal cells tend to persist (de Vos 1948, 1949).
Some information is taken from de Vos (1948, 1949) and Arekal (1967), all ovule and seed, Thompson (1976: vegetative; 1978 floral morphology), Rudall et al. (1998a: anatomy), Nordal (1998: general), Judd (2000 general), Kocyan and Endress (2001b: floral morphology), and Wiland-Szymanska (2009: general, east Africa).
Phylogeny. Kocyan et al. (2011) recovered three main clades - Curculigo et al., Pauridia et al., and Hypoxis - in the family, a slight modification of the results obtained by Rudall et al. (1998). Relationships between these clades was unclear.
Classification. For generic limits, see Kocyan et al. (2011).
Previous Relationships. Rudall (2003a) suggested that there might be a close morphological relationship between Hypoxidaceae and Orchidaceae. In older classifications, Hypoxidaceae were included in Amaryllidaceae.
[[Ixoliriaceae + Tecophilaeaceae] [Doryanthaceae [Iridaceae [Xeronemataceae [Xanthorrhoeaceae [Amaryllidaceae + Asparagaceae]]]]]]: ?
Age. The age of this node is estimated at ca 84 m.y. by Eguiarte (1995) and (98-)87, 78(-68) m.y. by Bell et al. (2010).
Phylogeny. This clade is strongly supported in analyses using data from four plastid genes (Fay et al. 2000; see also Chase et al. 2000a; Soltis et al. 2007a), but no morphological characters have yet been found for it. The positions of [Ixoliriaceae + Tecophilaeaceae] and Doryanthaceae are reversed in Kim et al. (2011).
[Ixioliriaceae + Tecophilaeaceae]: cormose; leaves spiral, base sheathing; flowers quite large; outer T mucronate to aristate, T tube short; A inserted at mouth of tube; embryo long; x = 12.
Age. For the age of this node, some (93-)79, 70(-59) m.y., see Bell et al. (2010). The divergence of the Ixoliriaceae is dated to ca 112 m.y. and that of Tecophilaeaceae to 108 m.y. (Janssen & Bremer 2004: note topology, but definitely rather older).
Chemistry, Morphology, etc. The outer tepals in at least some Iridaceae (and Orchidaceae!) are also mucronate to aristate.
Phylogeny. There is weak to moderate support for this taxon pair in Chase et al. (2000a), Pires et al. (2006), Givnish et al. (2006) and Seberg et al. (2012), and stronger support in Graham et al. (2006: sampling poor); they have a very long branch in the three-gene analysis of Fay et al. (2000). Davis et al. (2004) found some support for the clade [Ixoliriaceae + Iridaceae], although sampling was poor; Chase et al. (2006) found strong support for this relationship. Janssen and Bremer (2004) found pectinate relationships here: [Ixoliriaceae [Tecophilaeaceae [Doryanthaceae + the rest]]], while the relationships [Tecophilaeaceae [Doryanthaceae [Ixoliriaceae + Iridaceae]] the rest] in Chase et al. (2006) had very little support.
Previous Relationships. Both Dahlgren et al. (1985) and Takhtajan (1997) recognised relationships between Ixoliriaceae and Tecophilaeaceae, as well as with a selection of other asparagalean families.
IXIOLIRIACEAE Nakai Back to Asparagales
Plant a tunicated corm; saponins 0?; dimorphic exodermis 0; peduncle with a sclerenchymatous ring; mucilage cells +; leaf shortly cylindrical at apex, base ?type; inflorescence subumbellate, leafy; T tube short; A centrifixed; ovary inferior, stigma 3-lobed, dry; ovules many/carpel; seeds angled, phytomelan +; endosperm walls pitted, starch in cells surrounding embryo; cotyledon remains white even when exposed to light!
1[list]/3. Egypt to Central Asia (map: from Traub 1942, rather approximate). [Photo - Flower © A. Shoob]
Chemistry, Morphology, etc. The vascular bundles in the leaf are unequal in size, some in the inflorescence axis are arranged in a circle, enclosing additional scattered bundles.
Information is taken from Arroyo (1982) and Arroyo and Cutler (1984: both anatomy), and also from Kubitzki (1998b: general) and Dönmez and Isik (2008); see Tillich (2003) for seedling morphology.
Previous Relationships. The inflorescence axis is leafy, the flowers are blue and there are no alkaloids, all unusual features for Amaryllidaceae, where Ixiolirion was often included (Takhtajan 1997).
TECOPHILAEACEAE Leybold, nom. cons. Back to Asparagales
Corm tunicated (not); ?saponins +; stomata variable; (leaves with pseudopetiole, blade, and midrib, more than one order of parallel veins, [transverse veins branching, reticulated]), sheaths closed (none); inflorescence a raceme, branched or not, or flowers axillary; (bracteoles 0); flowers often monosymmetric; (T tube moderately long); (stamens of very different sizes), (stamens 4-3, staminodes 2-3), anthers dehiscing ± by pores; pollen operculate (not Kabayea and Cyanastrum); (G semi-inferior; carpels free - Cyanastrum), stigma punctate; ovules 2-many/carpel, ana-campylotropous, outer integument "thick", vascularized [Cyanastrum], obturator +; seed (one/fruit), phytomelan +/0, testa multilayered, (exotesta palisade), thick-walled; endosperm (nuclear - Cyanella), thick-walled, pitted or not, (± absent), ?starch (0, chalazosperm + - Cyanastrum), embryo also short; n = 8, 10-12, 14, chromosomes 2-4 µm long; cotyledon not photosynthetic, (coleoptile +), primary root long (hypocotyl and primary root 0 - Cyanastrum).
7[list]/25: Cyanella (9). Africa, Chile, and the U.S.A. (California - Odontostomum) (map: from Carter 1962; Scott 1991; Brummitt et al. 1998; Fl. N. Am. 26: 2002). [Photo - Flower, Flower.]
Age. Crown-group Tecophilaeaceae have been dated at ca 87 m.y. (Janssen & Bremer 2004) or ca 77 m.y.a. (Buerki et al. 2013a).
Evolution. Divergence & Distribution. Buerki et al. (2013a) discussed the complex eco-biogeographical history of this small clade, i.a. they noted that its colonization of what are now Mediterranean ecosystems occurred before the origin of the Mediterranean climate.
Chemistry, Morphology, etc. This is a heterogeneous group. Cells adjacent to stomata in Cyanastrum were described as having parallel cell divisions by Tomlinson (1974). The monosymmetry of the flower is largely caused by the androecium; enantiostyly also occurs in a few species of Cyanella. Odontostomum has been reported to have six staminodia alternating with the six stamens; the "staminodia" are some kind of corona or other enation from the tepals.
Some information is taken from Rudall (1997), Simpson and Rudall (1998), Brummitt et al. (1998) and Manning and Goldblatt (2012), that on ovules, from Nietsch (1941), and that on seedlings, which are variable in their morphology, from Tillich (1996a, 2003).
Phylogeny. Tecophilaea was found to be sister to the rest of the family, although with only moderate support; other relationships along the backbone were poorly resolved (Brummitt et al. 1998). More recently, Buerki et al. (2013a) found that the clade [Conanthera + Zephyra] (both genera are from South America) were sister to the rest of the family.
Classification. Given the poor support for many relationships here, a classification is premature (c.f. Brummitt et al. 1998); despite a more resolved phylogeny, Buerki et al. (2013) quite reasonably elect not to develop any formal suprageneric hierarchy.
Synonymy: Androsynaceae Salisbury, Conantheraceae Pfeiffer, Cyanastraceae Engler, Cyanellaceae Salisbury, Walleriaceae Takhtajan
[Doryanthaceae [Iridaceae [Xeronemataceae [Xanthorrhoeaceae [Amaryllidaceae + Asparagaceae]]]]]: ?
Age. this node has been dated to ca 107 m.y.a. (Janssen & Bremer 2004); the separation of Doryanthaceae from Iridaceae (sic) has been estimated at ca 82 m.y. (Goldblatt et al. 2008).
Pollen fossils assigned to Iridaceae-Isophysis or to Doryanthes have been found in Late Cretaceous rocks ca 75-70 m.y. old from Eastern Siberia (Hoffmann & Zetter 2010).
Phylogeny. There is only moderate support for this position in Fay et al. (2000) and practically no support in Seberg et al. (2012), but 92% bootstrap support in Graham et al. (2006: note sampling); see also Janssen and Bremer (2004).
DORYANTHACEAE R. Dahlgren & Clifford Back to Asparagales
Huge sub-bulbous tufted perennial; steroidal saponins +; vascular bundles encased in fibres; styloids +, raphides 0; cuticular wax rodlets parallel, stomata paracytic, subsidiary cells with oblique divisions; leaves spiral, when older with dry threads at apex; inflorescence with inflorescence bracts, (subumbellate); T large, tube long; (A also adnate to the base of the tepal lobes), anthers latrorse, centrifixed, endothecium thick; tapetal cells with several nuclei; pollen trichotomosulcate, surface reticulate; ovary inferior, stigma punctate, dry; ovules many/carpel, outer integument ca 5 cells across, inner integument ca 2 cells across, parietal tissue ca 5 cells across, nucellar cap ca 2 cells across, postament +; antipodal cells to 5, ± persistent; seeds flattened, winged; testa multiplicative, many-layered, with phlobaphene; endosperm helobial, thin-walled, embryo flattened; n = 17, 18, 22, 24, bimodal; seedling with laterally compressed haustorium, coleoptile +.
1[list]/2. E. Australia (map: from O. Seberg, pers. comm). [Photo - Habit.]
Chemistry, Morphology, etc. Kocyan and Endress (2001b) note that the connective is massive, each stamen being supplied by 2-4 "vascular complexes", although these were not observed by Newman (1928, 1929). There may be a hypostase immediately beneath the embryo sac, although there is also a great amount of tissue between it and the chalazal bundle (Newman 1928).
Much general information is taken from Wunderlich (1950) and Clifford (1998); Blunden et al. (1973) described leaf anatomy, and Tillich (2003) described seedling morphology.
Iridaceae [Xeronemataceae [Xanthorrhoeaceae [Amaryllidaceae + Asparagaceae]]]: (vegetative fructans, glucomannans +); (stem secondary growth +); (seeds with glucomannans as reserves); Arabidopsis-type telomeres lost, (TTAGGG)n [human-type telomeres] common.
Age. This node is estimated at (92-)81, 72(-62) m.y.o. by Bell et al. (2010).
Evolution. Divergence & Distribution. A distinctive pattern of secondary growth is scattered through this clade, and has also been reported from Eriocaulaceae (Poales: Scatena et al. 2005). A meristem cuts off tissue to the inside, and there separate vascular bundles embedded in ground tissue differentiate (Rudall 1991, 1995b for records and literature). Mangin (1882) had suggested there might be a connection between the origin of this secondary thickening and the reticulum of vascular bundles in association with which "adventitious" roots arise in monocots.
Genes & Genomes. The loss of Arabidopsis-type telomeres is not simple; human-type telomeres ((TTAGGG)n)) may predominate, but there are other types, too. Asparagaceae-Scilloideae agree with other members of this clade, although the Arabidopsis-type telomere is somewhat more common than in the other members sampled (Adams et al. 2001; especially Sýkorová et al. 2003b, 2006a, b). Acanthocarpus, alone among the taxa discussed there as being an out-group, also lacks the telomere, but it is in fact a member of Asparagaceae-Lomandroideae (ex Laxmanniaceae), an ingroup, not Dasypogonaceae, a commelinid.
Chemistry, Morphology, etc. Glucomannan seed reserves are reported from at least some members of this clade - Iridaceae, Asparagaceae-Asparagoideae and -Scilloideae-Ornithogaleae - and they are also known from some Liliales; the vegetative plants also may have distinctive carbohydrates (Jakimow-Barras 1973; Meier & Reid 1982; Buckeridge et al. 2000). Apparently there are only tracheids in the xylem (Fahn 1990). For secondary growth - perhaps the continued activity of the primary thickening meristem - see Rudall (1995b) and Carlquist (2012a).
Phylogeny. A group with quite strong support in Fay et al. (2000) and Soltis et al. (2007a), etc., but lacking much jackknife support in Seberg et al. (2012: bootstrap support better).
IRIDACEAE Jussieu, nom. cons. Back to Asparagales
Plant rhizomatous; roots mycorrhizal, root hairs 0; flavone C-glycosides, flavonols +, chelidonic acid 0?; dimorphic root hypodermis +; (stem endodermis +); raphides 0, styloids +; cuticular wax rodlets parallel; leaves two-ranked, unifacial, or isobifacial, equitant [oriented edge on to the stem], vernation plicate; flowers usu. large; T ± free, apex often aristate; A 3, opposite outer T, extrorse, endothecial cells with U-shaped thickenings; G opposite outer T, septal nectary 0, style branched (branches bifid), stigma on the edges of the complex/expanded branches, dry; ovules 1-many /carpel, micropyle endo- or exostomal, outer integument 4-6 cells across, parietal tissue 1(-2) cells across (absent); seed testal and tegmic, phytomelan 0, phlobaphene +, mesotesta 2-4 cells across, endotesta pigmented, with lipids; endosperm thick-walled, hemicellulosic, embryo quite large; cotyledon not photosynthetic, (with ligule or coleoptile - e.g. Tigridia), (photosynthetic - e.g. Sisyrinchium), (hypocotyl short).
66[list]/2035 (?2085) - eight subfamilies below. World-wide (map: see Heywood 1978 [S. America], Hultén & Fries 1986; Mathew 1989; Fl. N. Am. 26: 2002; Bahali et al. 2004; FloraBase 2005; Davies et al. 2005: Fig. 2b suggests that Iridaceae grow throughout Africa, much of the Arabian Peninsula, etc...; Rodrigues & Sytsma 2006; Alexeyeva 2008). [Photos - Collection.]
Age. Crown group divergence is estimated to have begun ca 96 m.y.a. (Janssen & Bremer 2004).
1. Isophysidoideae Thorne & Reveal
Vessel elements in roots with scalariform perforation plates; biflavonoids [amentoflavone] +; crystals 0 [leaves]; flower solitary, with spathes; endothecium with radially elongated walls; microsporogenesis?; G , style shortly branched, branches alternating with stamens; many ovules/carpel; endosperm ?helobial; n = ?; seedling?
1/1: Isophysis tasmanica. Tasmania.
Synonymy: Isophysidaceae F. A. Barkley
[Iridoideae [Patersonioideae [Geosiridoideae [Aristeoideae [Nivenioideae + Crocoideae]]]]]: xanthone + [mangiferin]; vessel elements in roots with simple perforation plates; inflorescence with cymose units in which the flowers arise successively from axils of the prophylls [i.e. alternating, = a rhipidium]; flowers short lived [open ca 1 day]; (pollen operculate [often with two exine bands in a sulcus]); G inferior; endosperm nuclear.
2. Iridoideae Eaton
(Plant bulbous); gamma-glutamyl peptides, metacarboxy amino acids +; vessel elements in root with simple perforation plates, (vessels in stems and leaves - Sisyrinchium); (leaf vernation plicate); rhiphidia simple; (flowers long-lived; monosymmetric; T whorls strongly differentiated (not); A 2 - Diplarrhena); T nectaries +, (oil glands or oil hairs +); endothecial cells with spiral thickenings [not Sisyrinchium]; (pollen grains with encircling aperture); (septal nectaries + - Diplarrhena), style branches long, tubular, (branches alternating with anthers, Sisyrynchium et al.); n = ?.
30/820: Iris (280, inc. Belamcanda), Moraea (200), Sisyrinchium (60-260), Tigridia (50). Worldwide, but esp. the spine of Central and South America.
[Patersonioideae [Geosiridoideae [Aristeoideae [Nivenioideae + Crocoideae]]]]: rhipidia 2, fused [binate], each unit with 2-many flowers; T connate; ; extra codon in rps4 gene.
3. Patersonioideae Goldblatt
Plant ± woody and rhizomatous; biflavonoids [amentoflavone] +; stem secondary growth +; vessel elements in roots often with scalariform perforation plates; inner tepals reduced to scales or 0; endothecial cells with base-plate thickenings, filaments ± connate; pollen spherical, inaperturate, intectate; embryo small; n = 11, 21; two extra codons in rps4 gene.
1/24. More or less open conditions, scattered in Malesia, New Caledonia, and the periphery of Australia (map: partly from Fl. Austral. 46. 1986).
[Geosiridoideae [Aristeoideae [Nivenioideae + Crocoideae]]]: ?
4. Geosiridoideae ("Geosiridaceae") Goldblatt & Manning
Plant echlorophyllous, myco-heterotrophic; crystals 0 [leaves]; leaves heterobifacial; flowers sessile; T connate basally only; microsporogenesis successive; ovules with parietal tissue 1-2 cells across; seeds minute, dust-like, mesotesta 0; endosperm helobial, starchy, walls thick, hemicellulosic, embryo small; n = ?
1/2. Madagascar, the Comores.
Synonymy: Geosiridaceae Jonker
[Aristeoideae [Nivenioideae + Crocoideae]]: ?
Evolution. Divergence & Distribution. The age of this node is estimated at (49-)34, 31(-17) m.y. by Bell et al. (2010).
5. Aristeoideae Vines
Plumbagin +; vessel elements in roots often with scalariform perforation plates; leaf bundles embedded, marginal sclerenchyma 0; T connate basally only; embryo small; n = 16.
1/55. More or less open conditions, sub-Saharan Africa and Madagascar.
[Nivenioideae + Crocoideae]: flowers long-lived; septal nectary +.
6. Nivenioideae Goldblatt
Plant with woody stem; secondary thickening +; leaves with non-vascular fibrous strands; unit of rhipidium with 1-2 flowers; P long-tubular, T clawed (short-tubular, T long-linear - Klattia); endothecial cells with basal anastomosis of U-shaped thickenings; (pollen grains with encircling sulcus); stigmas simple, not or somewhat expanded; ovules 2/carpel; 1 shield-shaped [tangentially flattened] seeds per loculus; exotesta transparent, mesotesta 0-1 cell across; n = 16.
3/14. Only in the S.W. Cape region, South Africa
6. Crocoideae G. T. Burnett
Plant with corms; vessel elements in root with simple perforation plates; (mesophyll cells laterally elongate); (leaf vernation plicate), when flat with pseudomidrib (not Pillansia), sheath closed; inflorescence spicate; rhipidium binate, with a single flower, pedicel 0; (flowers short-lived), variously monosymmetric (polysymmetric); anther endothecium with spiral thickenings; pollen exine tectate, perforate-scabrate, aperture with one or a pair of longitudinal bands forming operculum, (zona-aperturate); (septal nectaries 0); ovules campylotropous, hypostase prominent, postament +; n = 3-17, etc.
28/1005: Gladiolus (260), Romulea (90), Geissorhiza (85), Crocus (100 [?150]), Hesperantha (80), Babiana (55), Watsonia (50), Ixia (50). Overwhelmingly southern African, to Europe, Madagascar and Central Asia.
Synonymy: Crocaceae Vest, Galaxiaceae Rafinesque, Gladiolaceae Rafinesque, Ixiaceae Horaninow
Evolution. Divergence & Distribution. Davies et al. (2005) discuss diversification rates. The family has clades with a disproportionately large number of species in e.g. southern Africa, but less so in the north temperate zone. Iridaceae are one of the major geophytic groups of the Cape (Procheŝ et al. 2006) with more than 650 species there; Davies et al. (2004c) see this diversification as the result of the interaction of local features such as traits affecting reproductive isolation and the ecological and climatic heterogeneity of the area. Davies et al. (2005) noted that in Iridaceae diversification was greater in areas like southern Africa than in the northern hemisphere.
Indeed, the Cape area seems to be notably diverse from a global point of view (Kreft & Jetz 2007). For the radiation of the Cape genus Moraea, both cytologically and florally diverse, see Goldblatt et al. (2002); radiation in this and other iridaceous Cape genera may have begun in the fynbos in the Miocene some 25 m.y.a., divergence in the succulent Karoo being more recent (Verboom et al. 2009). Diversification of two geophytic Cape genera, Babiana, with ca 92 species nearly all from the Greater Cape floristic region, and Moraea, with over 150 species in Cape region, may in part be connected with soil type preferences changing during speciation; here diversification began a mere 17-15 m.y.a. in the mid-Pliocene (Schnitzler et al. 2011); diversification rates in the Cape region and outside are largely similar (Silvestro et al. 2011).
Pollination Biology & Seed Dispersal. Iridaceae show considerable floral diversification, ranging from the open flowers of Sisyrinchium to the meranthia of Iris et al. and the tubular flowers of Gladiolus et al. (e.g. Bernhardt & Goldblatt 2006 and references; Rodrigues & Sytsma 2006; Wilson 2006). In Iris and its relativesthe flower will appear to the pollinator as if were really three monosymmetric flowers. There the tepaloid style overarches the stamen opposite it and the landing platform for the pollinator is a member of the outer perianth whorl underneath the style/stamen complex. However, in Cypella the three landing platforms for the pollinating bee are members of the inner perianth whorl. Here the pollen deposited on the backs of the bees comes from half anthers of adjacent stamens and is deposited on the receptive surfaces of two adjacent half-stigmas (Vogel 1974).
The flowers of Gladiolus (Crocoideae) are obliquely monosymmetric, although this is hardly apparent in the open flower due to changes in orientation as the flower and inflorescence grow. Tepal patterning, where it occurs, is usually on an adaxial lateral member of the outer whorl and adjacent members of the inner tepal whorl and is clearly on the adaxial side of the flower, but it may be on an adaxial lateral and the abaxial member of the outer whorl and a tepal of the inner whorl between them (Eichler 1875; Choob 2001). Although it is likely that other Crocoideae show the same oblique monosymmetry, monosymmetry in Diplarrhena (Iridoideae) appears to be vertical; that genus has only two stamens and one staminode. Interesting infraspecific variation occurs. In some flowers of Crocosmia X crocosmiiflora the odd member of the outer whorl was adaxial while in others it was abaxial; the patterning of the tepals, etc., varied accordingly (pers. obs.). All told, well over half the family has monosymmetric flowers of one sort or another, and the evolution of monosymmetry in the family will repay further study (see also Davies et al. 2004b).
Much work has been carried out on pollination in Iridaceae, particularly on species from the sub-Saharan region, especially in South Africa, where nearly all the species are morphologically specialized, if on generalized pollinators (Goldblatt and Manning 2006, also 2008 for a general account; Johnson 2010). Floral homoplasy is very extensive in Iridoideae-Tigridieae (Rodrigues & Sytsma 2006), -Trimezieae (Lovo et al. 2012), and -Irideae (in Iris itself - Wilson 2006). Many different kinds of pollinator are involved. Thus Babiana (Crocoideae) is pollinated by birds, scarab beetles, bees, moths, etc. (Bernhardt & Goldblatt 2006; esp. Goldblatt & Manning 2007), while scarabeid monkey beetles pollinate the flowers of three Cape genera of Iridaceae that have distinctive dark markings at the bases of the tepals (van Kleunen et al. 2007). At least 34 southwest African Iridaceae are pollinated by three species of (extremely) long-tongued dipteran nemestrinid flies; the long-tubed monosymmetric flowers pollinated by these flies have evolved several times there as well as in unrelated groups (Manning & Goldblatt 1996, 1997). There are a number of oil flowers in Iridaceae, including Cypella (see above), ca 35 species of Sisyrinchium from South America, and some other New World Iridoideae like Tigridia (Renner & Schaefer 2010); oil-secreting trichomes appear to have evolved twice in Sisyrinchium alone (Chauveau et al. 2011). Indeed, these trichomes vary both in morphology and position in flowers of New World Iridaceae (Silvério et al. 2012); evolution of floral rewards in these taxa has a complex pattern of gains, changes and losses (Chauveau et al. 2012).
Vegetative Variation. Some taxa are more or less woody, and monocot-type secondary thickening has been reported from them; the vessel elements in the roots of such plants often have scalariform perforation plates (Cheadle 1964: inc. Klattia). Foliar variation is considerable. Thus some taxa have terete, unifacial leaves, others apparently ordinary heterobifacial leaves (even some Iris), many have ensiform isobifacial leaves, as in Gladiolus, most Iris, etc., others are strangely ribbed, but in transverse section they all seem to be modifications of a basic unifacial leaf theme (e.g. Ross 1892, 1893; Arber 1925; Rudall 1991); Geissorhiza alone has ligulate leaves. Crocus has revolute leaves with a unifacial midrib, and Romulea seems to be a modification of this. For water-catching leaves of Iridaceae with very distinctive morphologies that are found especially in taxa from Namaqualand, see Vogel and Müller-Doblies (2011).
Genes & Genomes. For cytological evolution in Crocus, n = 3<, see Harpke et al. (2013); multiple hybridizations, dysploidy events, and evolution of B chromosomes are all involved.
Chemistry, Morphology, etc. For the occurrence of plumbagin in Aristea, see Harborne and Williams (2001). Homeria and Moraea (Iridoideae) have bufadienolides (cardiac glycosides: Harborne & Williams 2001). Iris contains a greater diversity of isoflavonoids than any other group outside Fabaceae (Reynaud et al. 2005); for xanthones, especially in Iris, see Williams et al. (1997b).
Goldblatt (1990) interpreted the paired "bracts" below the single flowers of Isophysis as representing a reduced rhipidium, a monochasial cymose inflorescence - a rhipidium may then be another synapomorphy for the family. Some species of Nivenia are heterostylous, a very uncommon condition in the monocots. Aristea is palynologically very variable, some members even having disulcate pollen (see Goldblatt & Le Thomas 1997; le Thomas et al. 2001). In Sisyrinchium and its relatives the style branches alternate with the stamens; elsewhere the two are usually on the same radius. For a discussion of the caruncles/arils of Iris, see Wilson (2006).
Additional gneeral information is taken Goldblatt et al. (1998), Goldblatt (2001), and Goldblatt and Manning (2008); see also Mathew (1989: Iris in the old sense and its relatives), Rübsamen-Westenfeld et al. (1994: Geosiris), Rudall et al. (1986) and Rudall (1995a), both anatomy, Goldblatt et al. (1984: crystals), Manning and Goldblatt (1990: endothecial thickenings), Wilson (2001: embryology of Iris), Cocucci and Vogel (2001: nectaries), Tillich (2003a: seedlings - very variable), Rudall et al. (2003a: nectary evolution), and Dönmez and Isik (2008: pollen).
Phylogeny. Iridaceae are monophyletic in nearly all studies (but c.f. Chase et al. 1995a). Initial resuls suggested that the monotypic Isophysidoideae were sister to the rest of the family, Crocoideae and Iridoideae appeared to be monophyletic, but the status of Aristeoideae was unclear. Reeves et al. (2001a, b: four genes) found that Patersonia, Geosiris, and Aristea were successively sister to a large clade making up [Aristeoideae + Crocoideae]; support was mostly moderate (see also Teixeira de Souza-Chies et al. 1997). If these relationships were confirmed, either the circumscription of Crocoideae would have to be considerably extended, or three more subfamilies would be needed. Goldblatt et al. (2008: five plastid genes) took for this latter option; they found strong support for the pectinations basal to Crocoideae s. str., albeit using successive weighting, which tends to leave one a little uneasy. See Rudall (1994c) for a morphological phylogeny.
Within Iridoideae, the Australian Diplarrhena, whose monosymmetric flowers have only two stamens and pollen grains that are spherical, inaperturate, and intectate pollen, may be sister to the rest (Reeves et al. 2001a, b; Rudall et al. 2003a). The five tribes in Iridioideae are quite well supported and have well-resolved relationships: [Diplarreneae [Irideae [Sisyrincheae [Trimezieae + Tigridieae]]]] (Goldblatt & Manning 2008; also Golblatt et al. 2004, 2006). For diversification of the American Tigridieae, see Rodrigues and Sytsma (2006). Relationships within Trimezieae are being clarified (Lovo et al. 2012). For a phylogeny of Iris, see Tillie et al. (2001) and Wilson (2004); there is phylogenetic resolution of the major groups in the genus (Wilson 2011). Karst and Wilson (2012) obtained a fair degree of resolution in relationships within New World Sisyrinchium, although species limits there are in a considerable state of disarray (see also Chauveau et al. 2011).,/p>
Within Crocoideae there are five tribes, but these were mostly only moderately supported and their relationships poorly resolved (Goldblatt & Manning 2008; also Goldblatt et al. 2004). Tritoniopsis, with a tubular cotyledonary sheath and tubular cataphyll, may be sister to the rest of the subfamily, but support is at best moderate (Goldblatt et al. 2006; Golblatt & Manning 2008). For a phylogeny of Crocus see Petersen et al. (2008, c.f. in part Frello et al. 2004), and especially Harpke et al. (2013). See Goldblatt and Manning (1998) for a treatment of much of Gladiolus.
Classification. I follow the classification suggested by Goldblatt et al. (2008); the subfamilies are for the most part well characterised. See Goldblatt and Manning (2008) for an account of the genera and Wilson (2011) for an infrageneric classification of Iris.
[Xeronemataceae [Xanthorrhoeaceae [Amaryllidaceae + Asparagaceae]]]: mitochondrial rpl2 gene lost.
Age. The age of this node is around (84-)74, 67(-57) m.y. (Bell et al. 2010) or ca 100 m.y. (Janssen & Bremer 2004).
Phylogeny. This is a strongly supported group in Fay et al. (2000) and Soltis et al. (2007a); see also Janssen and Bremer (2004). The loss of the mitochondrial rpl2 gene occurs either at this node or the next up the tree (see Adams et al. 2002b).
XERONEMATACEAE M. W. Chase, Rudall & Fay Back to Asparagales
Plant rhizomatous; leaves two-ranked, equitant and isobifacial [oriented edge on to the stem]; inflorescence branched, with inflorescence bracts, densely spicate; flowers large; stamens long-exserted, anthers centrifixed; pollen boat-shaped; style solid; n = 17, 18.
1/2. New Zealand (Poor Knights Island) and New Caledonia.
Chemistry, Morphology, etc. The family is little known, although there is some information in Chase et al. (2000c); the style is scored as if it is hollow in Rudall (2003a).
Previous Relationships. Xeronemataceae were provisionally placed in Asphodelaceae by Takhtajan (1997) and in Hemerocallidaceae by Clifford et al. (1998).
[Xanthorrhoeaceae [Amaryllidaceae + Asparagaceae]]: (pedicels articulated); septal nectaries infralocular; ovules with parietal tissue 2-3 cells across.
Age. The age of this node is some (72-)64, 58(-49) m.y. (Bell et al. 2010), ca 93 m.y. (Janssen & Bremer 2004) or 61-54 m.y. (Wikström et al. 2001).
For the optimisation of characters like "septal nectaries infralocular" and "overy superior", see the beginning of this page. The optimisation of successive microsporogenesis on the tree is also uncertain (Chase et al. 2000a); for instance, microsporogenesis varies within Xanthorrhoeaceae.
Chemistry, Morphology. For chromosome sizes of a number of taxa in the group, see Vijayavalli and Mathew (1990 - as Liliaceae). Schnarf and Wunderlich (1939) provide some embryological details and El-Hamidi (1952) some for the gynoecium from scattered taxa in "Asphodeloideae"; the latter found substantial similarity between all the taxa he examined except Aphyllanthes.
Phylogeny. This clade has strong support in Fay et al. (2000) and Chase et al. (2000b).
XANTHORRHOEACEAE Dumortier, nom. cons. Back to Asparagales
(Vessel elements in roots with simple perforation plates); styloids +; (stomata paracytic, subsidiary cells with oblique divisions); leaf sheath closed; inflorescence scapose; pedicels articulated; (A not adnate to T); outer integument ³3 cells across, hypostase +; cotyledon not photosynthetic.
35/900. Esp. Old World, not Arctic, western South America.
Age. The crown group is dated to ca 90 m.y. (Janssen & Bremer 2004). Bell et al. (2010), on the other hand, estimate the crown-group age at (66-)52, 47(-36) m.y.
1. Asphodeloideae Burnett
Often rosette-forming leaf succulents, geophytic (rhizomatous) herbs to pachycaul trees, (climbers); monocot secondary thickening widespread; tetrahydroanthracenones + [e.g. chrysophanol]; (velamen +); foliar vascular bundles often inverted, parenchymatous cells in the inner bundle sheath adjacent to the phloem [aloin cells], (sclerenchymatous); leaves spiral or two-ranked, margins often spiny-toothed, (leaf base not sheathing); inflorescence also spicate; (pedicels not articulated), ± weak monosymmetry common; T ± free (connate - Kniphofia, etc.); (anthers centrifixed); microsporogenesis simultaneous; (pollen mixed with raphides); stigma dry (wet); ovules 1-many/carpel, hemitropous, (± straight - Asphodelus clade), outer integument 3-4 cells across, parietal tissue 1 (2) cells across, hypostase +; (capsule fleshy); seed ± angled, aril +, funicular (thin); endosperm thick-walled, hemicellulosic[?], (perisperm +, slight), embryo long; n = (6 - Kniphofia) 7, chromosomes 1.5-20 µm long, usu. bimodal; 3'-rps12 intron lost; (coleoptile +).
Ca 15[list]/785: Aloe (400), Haworthia (54-70), Bulbine (75), Kniphofia (70),Trachyandra (50), Eremurus (45). Africa, esp. South Africa; also the Mediterranean to Central Asia, Australia, New Zealand (map: see Reynolds 1966; Frankenberg & Klaus 1980; Seberg 2007). [Photo - Collection, Inflorescence, Flowers.]
Synonymy: Aloaceae Batsch, Asphodelaceae Jussieu, nom. cons.
[Xanthorrhoeoideae + Hemerocallidoideae]: anthraquinones +; raphides 0.
2. Xanthorrhoeoideae M. W. Chase, Reveal & M. F. Fay
Stem thick, woody, erect (not); secondary thickening +; plant resiniferous; ?vessels; layer of sclerenchyma below epidermis in leaves; stomata paracytic; leaves spiral, unifacial, leaf base not sheathing; inflorescence densely spike-like, branches cymose, congested; flowers sessile, not articulated; T = 3 dry + 3 subpetal-like, free; stamens long exserted; microsporogenesis successive [tetrads tetragonal]; pollen extended sulcate; stigma ± punctate, ?wet; ovules several/carpel, outer integument ca 3 cells across, apex of nucellus pointed, hypostase?; inner cuticle of tegmen +; seeds flattened; endosperm quite thick-walled, development?, little hemicellulose, embryo transverse to long axis of seed; n = 11, (bimodal); hypocotyl short.
1[list]/30. Australia (map: see Fl. Austral. 46. 1986). [Photo - Habitat, - Habit, Inflorescence.]
3. Hemerocallidoideae Lindley
Habit various; flavonols, naphthoquinones, saponins +; roots often swollen; (vessels in the stem); mucilage cells 0; cuticular wax rodlets parallel; leaves (spirally) two-ranked, vernation conduplicate to flat-conduplicate or plicate, (semi-ensiform, isobifacial); inflorescence various; (bracteoles lateral), (flowers monosymmetric); (median tepal of outer whorl adaxial - Hemerocallis), T tube short (1/2 way - Hemerocallis; 0); filaments often ornamented/swollen, (anthers (centrifixed), dehiscing by pores - Dianella and relatives); microsporogenesis simultaneous (successive), pollen trichotomosulcate (monosulcate); stigma dry (wet), (3-parted - Pasithea); ovules 1-many/carpel, outer integument 6-7 cells across, inner integument 2-4 cells across, parietal tissue absent, nucellar cap ca 2 cells across (0), podium well developed, hypostase 0; antipodal cells large, persistent; fruit also a berry (nut); seeds ovoid, (flattened - Phormium), (with strophiole/aril - Johnsonia et al.;); endosperm hemicellulosic, usu. helobial, embryo also short; n = 4 [Agrostocrinum], 8, 9, 11, 12, chromosomes 0.8-17.33 µm long; (cotyledon not photosynthetic - Dianella), epicotyl long or not (hypocotyl 0; collar +), primary root well developed, branched or not.
19[list]/85. Papuasia to New Zealand and the Pacific, esp. Australia (e.g. all 8 genera of Johnsonieae s. str.), also Europe to Asia, Malesia, India, Madagascar, Africa; two genera and two species in South America (map: from Fl. Austral., Wurdack & Dorr 2009). [Photo - Habit, Flower, Flower].
Synonymy: Dianellaceae Salisbury, Eccremidaceae Doweld, Geitonoplesiaceae Conran, Hemerocallidaceae R. Brown, Johnsoniaceae J. T. Lotsy, Phormiaceae J. Agardh
Evolution. Divergence & Distribution. Eccremis and Pasithea represent independent migrations of the phormioid clade to South America (Wurdack & Door 2009), while Bulbinella (Asphodeloideae) grows in South Africa and New Zealand.
For an ecological account of Xanthorrhoea, see Lamont et al. (2004); some diversification in the genus may be associated with the aridification of the Nullarbor Plain some 14-13 m.y.a. separating eastern and western clades (Crisp & Cook 2007).
Vegetative Variation. Most members of the phormioid clade have leaves that are more or less isobifacial and equitant immediately above the sheath, but higher up they become dorsiventrally flattened and more "normal" in appearance; Pasithea, sister to the rest of the clade, lacks this isobifacial zone (Wurdack & Dorr 2009). Members of Asphodeloideae have more or less succulent leaves, and species of Aloe and Haworthia in particular are commonly rosette plants with massively fleshy leaves; these can be borne in spirals or be distinctively two-ranked. As with Aizoaceae from southern Africa, there is great variation in the micromorphology of their epidermis (Cutler 1982); the two grow in similar extreme habitats. For the water-catching leaves in taxa growing in foggy deserts in Namaqualand, see Vogel and Müller-Doblies (2011). Geitonoplesium (Hemerocallidoideae) has resupinate leaves.
Pollination Biology & Seed Dispersal. Many species of Aloe (Asphodeloideae) are pollinated by birds, but insect pollination is also known here, as in other groups of Asphodelaceae; the directionality of evolution of pollinator relationships is unclear (Hargreaves et al. 2008). The floral monosymmetry that occurs in Haworthia and relatives is rather weak. Hemerocallidoideae often have rather elaborate stamens.
A number of Hemerocallidoideae have myrmecochorous seeds (Lengyel et al. 2010).
Chemistry, Morphology, etc. Within Asphodelaceae, the old Alooideae (= Asphodeloideae, part) are chemically very distinctive (Klopper et al. 2010 for a summary). Aloin, an anthraquinone glycoside, is a laxative commonly found in Aloe. Members of the old Alooideae have 1-methyl-8-hydroxyanthraquinones, e.g. chrysophanol, in the roots and anthrone-C-glycosides in the leaves. In Asphodeloideae Bulbine, Trachyandra, and Kniphofia all have knipholone, an anthraquinone derivative (van Wyck et al. 2005), but it appears not to have been reported from the Asphodelus clade. Johnsonia (Hemerocallidoideae) has chelidonic acid (Ramstad 1953).
The apical meristem of the stem in Xanthorrhoea media is massive - 580-1283 µm across (Staff 1968, q.v. for details of stem growth). The sieve tube plastids of the Aloe group also have peripheral fibres in addition to the central protein crystal. Aloin cells are reported from Dianella (Hemerocallidoideae: see Rudall 2003a); on the other hand, Kniphofia lacks aloin cells, having a well developed sclerenchymatous cap in their place (as have some other Asphodelaceae, even some Alooideae). It is unclear if aloin cells are secretory (Beaumont et al. 1985: survey and chemistry). The vascular bundles in the leaf form a circle and there are globules in the outer bundle sheath (also in Kniphofia); the central cells of the leaf are gelatinous. The old Aloideae are reported to have tetracytic stomata (e.g. Cutler 1972), although this is questioned by G. Smith and van Wyk (1992).
The inflorescences of Xanthorrhoea are described as being terminal (Clifford 1998); I do not know if they are always terminal in Asphodeloideae. Hemerocallis also seems to have lateral bracteoles, as does Dianella; both may have "inverted" flowers (e.g. Eichler 1875; Ehrhardt 1992), although in Hemerocallis, at least, this seems to be variable. Hemerocallis flowers with the median outer tepal adaxial are common, but the seal of the Daylily Society shows a flower with the normal monocot orientation! The number of vascular bundles supplying the tepals in members of this subfamily varies from (1-)3-9(-25) (Clifford et al. 1998a). Both Hemerocallidoideae and Xanthorrhoeoideae have ovaries that can be interpreted as being secondarily superior and that have infra-locular septal nectaries (Rudall 2002, 2003a). In at least some species of Aloe the larger stamens are opposite the inner whorl of tepals. Ovule orientation at the basal node in the family is unclear (c.f. Steyn & Smith 1998). Kniphofia has a bistomal micropyle and a nucellar endothelium (Takhtajan 1985). Daru et al. (2013) noted that seedlings of Aloe and Gasteria have two-ranked leaves, whatever the leaf arrangement in the adults.
There is variation in microsporogenesis in Hemerocallidoideae. Microsporogenesis in Hemerocallis was described as being successive and the endosperm as being nuclear by Di Fulvio and Cave (1965, but c.f. Cave 1955). Hemerocallis also has isoflavones, monosulcate pollen and a wet stigma, but it lacks a nucellar cap and septal nectaries. In pollen morphology Hemerocallis was considered to be derived by Chase et al. (1996); with Simethis), it is sister to the rest of Hemerocallidoideae (see also McPherson et al. 2004; Wurdack & Dorr 2009 - is microsporogenesis in the latter known?).
For general information, see G. Smith and Van Wyk (1998), Clifford and Conran (1998: Johnsoniaceae), and Clifford et al. (1998a), see also Riley and Majumdar (1979: biosystematics), Van Wyk et al. (1995, 2005) and Grace et al. (2010:), all chemotaxonomy, Kite et al. (2000: anthroquinones), G. Smith et al. (1992: anatomy), Cave (1955, 1975), Raju (1957), Berg (1962) and di Fulvio and Cave (1965), all embryology, Steyn and Smith (1998: ovule morphology, 2001), Reynolds (2004: esp. Aloe), Ely and Luque Arias (2006: anatomy of Eccremis), and Kosenko (1994: pollen of Phormium).
For Xanthorrhoea, some information is taken from Chanda and Ghosh (1976: pollen), Rudall (1994b: embryology), Rudall and Chase (1996: phylogeny) and Bedford et al. (1986) and Clifford (1998), both general.
Phylogeny. There is strong support for Xanthorrhoeaceae s.l. in Fay et al. (2000), Wurdack and Dorr (2009), etc. However, relationships within the clade were initially unclear. There is slight support for a [Xanthorrhoeoideae + Asphodeloideae] clade in the three-gene tree of Chase et al. (2000a; see also Fay et al. 2000); some analyses in Chase et al. (2000a) also suggested an [Asphodeloideae + Hemerocallidoideae] clade. However, Devey et al. (2006) found support for a [Xanthorrhoeoideae + Hemerocallidoideae] clade (see also Pires et al. 2006; Graham et al. 2006; Wurdack & Dorr 2009: good-moderate support; Seberg et al. 2012; Steele et al. 2012: strong support). Rudall (2003a) suggested that there were close morphological relationships between Hemerocallidaceae (Hemerocallidoideae) and Asphodelaceae (Asphodeloideae) - and between Xanthorrhoeaceae s. str. and Iridaceae...
Within Asphodeloideae, Aloe and its immediate relatives (= Alooideae: Klopper et al. 2010 for a summary) seem distinct and form a monophyletic group. However, more ordinary-looking Bulbine is sister to this clade, and then come other Asphodeloideae, including Kniphofia et al. and Eremurus et al. (relationships around here unclear); the [Asphodelus + Asphodeline] clade is sister to the rest of the subfamily (good support; n = 14) (see Devey et al. 2006 for a phylogeny, inc. details of that of Bulbine, also references below). Some species of Bulbine have a bimodal karyotype of n = 7, 4 long and 3 short (Spies & Hardy 1983), rather like the karyotype of Aloeae (4L + 3S: probably evolved independently, see Chase et al. 2000a; Devey et al. 2006; Pires et al. 2006), and they also have similar medicinal properties... For relationships around Aloe, which remain poorly understood and little resolved, see Treutlein et al. (2003a, b) and Daru et al. (2013), in Kniphofia, see Ramdhani et al. (2009), and for those around Haworthia, see Ramdhani et al. (2011).
There are two well supported clades within Hemerocallidoideae, the phormioid and [hemerocallid + johnsonioid] clades (e.g. Wurdack & Dorr 2009; also Seberg et al. 2012). The loss of the 3'-rps12 intron characterises the [hemerocallid + johnsonioid] clade (= [Johnsonieae + Hemerocallis + Simethis]), see McPherson et al. (2004) and Chase et al. (2000b). Pasithea, from South America, is sister to all other phormioids (Wurdack & Dorr 2009; Seberg et al. 2012), while the other New World genus, Eccremis, previously of uncertain relationships (e.g. Clifford et al. 1998a) because of interpretations of morphology, is sister to Dianella of the Johnsonieae (Wurdack & Dorr 2009).
Classification. A.P.G. II (2003) suggested as an option the inclusion of Asphodelaceae, Xanthorrhoeaceae and Hemerocallidaceae in Xanthorrhoeaceae s.l., and this circumscription was adopted by A.P.G. III (2009). The subfamilial classification above follows that in Chase et al. (2009b). The recognition of Alooideae (= Asphodeloideae: Aloeae) would make Asphodeloideae paraphyletic and necessitate the recognition of several other subfamilies.
G. Smith and Steyn (2004) discuss the taxonomy of Alooideae; generic limits around Aloe are decidedly unsatisfactory (e.g. Treutlein et al. 2003a, b; Klopper et al. 2010), while species limits are also problematic there, and in Kniphofia (Ramdhani et al. 2009), Haworthia (Ramdhani et al. 2011: ?hybridization; Bayer 2009: some comments and references). Species estimates in Dianella (Hemerocallidoideae) range from 25-350+ (Carr 2007). Carter et al. (2011) offer a well-illustrated account of Aloe (500+ species?).
Thanks. I thank Syd Ramdhani and Matt Ogburn for useful discussions.
Previous Relationships. Three genera that used to be placed in Asphodelaceae s. str. are now in Hemerocallidoideae (Simethis), Asparagaceae-Asparagoideae (Hemiphylacus), and Asparagaceae-Agavoideae (Paradisea, Anthericaceae s. str.) respectively - the evidence is largely molecular (Chase et al. 2000b).
[Amaryllidaceae + Asparagaceae]: microsporogenesis successive [possible place]; endosperm development?
Age. This node is ca 91 m.y.o. (Janssen & Bremer 2004), 58-51 m.y. (Wikström et al. 2001), or (69-)60, 54(-45) m.y. (Bell et al. 2010).
Chemistry, Morphology, etc. Where do steroidal saponins occur in this clade? Microsporogenesis is uniform here. In other Asparagales with successive microsporogenesis, details of wall formation (centrifugal cell plates) is similar to those members of this clade that have been studied, however, plate formation may also be centripetal when microsporogensis is simultaneous (Nadot et al. 2006). For chromosome size in Liliaceae s.l. and relatives, i.e. some taxa in this area, see Vijayavalli and Mathew (1990).
Phylogeny. This is a strongly supported clade (e.g. Chase et al. 1995a; Fay et al. 2000; Chase et al. 2000b; Graham et al. 2005), however, inclusion of Aphyllanthes in analyses has tended to decrease support for the clades within it (Graham et al. 2006). Kim et al. (2011: seven genes, three compartments) found that Amaryllidaceae grouped with Asparagoideae, Lomandroideae and Nolinoideae; other members of this clade formed a separate group.
AMARYLLIDACEAE J. Saint-Hilaire, nom. cons. Back to Asparagales
Leaves two-ranked; inflorescence scapose, umbellate, cymose, inflorescence bracts 2 or more, scarious, internal bracts small; pedicels not articulated; (T free); (A connate basally), (tapetal cells uninucleate); style long, stigma dry; parietal tissue absent; endosperm nuclear or helobial; hypocotyl 0.
73/1605. Worldwide - three subfamilies below.
Age. Crown-group Amaryllidaceae are ca 87 m.y.o. (Janssen & Bremer 2004).
Bacterial/Fungal Associates. Fungi on Allium and other Allioideae are rather different from those on Amaryllidoideae (e.g. Savile 1962).
Chemistry, Morphology, etc. Distinctive, mannose-binding lectins (the specificity is absolute) are found in Allioideae and Amaryllidoideae (van Damme et al. 1991: known from Agapanthus?). Very large genomes with a C value of some 350 picograms or more are found in some Amaryllidaceae-Allioideae and -Amaryllidoideae - also in Asparagaceae-Scilloideae (Leitch et al. 2005). For tapetal cells, see Wunderlich (1954), for inflorescence structure, see Weberling (1989).
Phylogeny. This is a very strongly supported clade (e.g. Fay et al. 2000, but c.f. McPherson et al. 2004; Thomas et al. 2005), and it has some characters! Meerow et al. (1999), Fay et al. (2000: strong support), Givnish et al. (2006), Pires et al. (2006) and Seberg et al. (2012: support weak) suggest a set of relationships [Agapanthaceae [Alliaceae + Amaryllidaceae]], although Meerow et al. (2000a) found Agapanthaceae to be sister to Amaryllidaceae, albeit with weak support.
Classification. Combining the three families Agapanthaceae, Alliaceae and Amaryllidaceae into Alliaceae s.l. was an option in A.P.G. II (2003), an option that was exercised in A.P.G. III (2009), although under the name of Amaryllidaceae. The infrafamial classification follows that in Chase et al. (2009b).
1. Agapanthoideae Endlicher
Plant rhizomatous; velamen +; laticifers +?; leaf vernation flat; inflorescence bracts connate along one side, other bracts?; flowers large, weakly monosymmetric; T ± connate basally; anther middle layer of wall from outer secondary parietal cells; ovules apotropous; seeds flat, winged; endosperm with starch/hemicellulose, embryo short; n = (14) 15 (16), chromosomes 4-9 µm long; seedling as in Allioideae?
1/9. South Africa (map: from Leighton 1965). [Photo - Habit, Flower.]
Chemistry, Morphology, etc. Information is taken from Kubitzki (1998b: general); D. Zhang et al. (2010) describe sporogenesis and gametogenesis (there are reports of occasional embryos with two cotyledons), and Zhang et al. (2011) embryogeny.
Synonymy: Agapanthaceae F. Voigt
[Allioideae + Amaryllidoideae]: plants geophytes, bulbs +, tunicate, with contractile roots; lectins binding mannose; (embryo sac bisporic, eight nucleate).
Age. The age of this node is estimated at (62-)50, 46(-35) m.y. by Bell et al. (2010).
2. Allioideae Herbert
Flavonoids, cysteine-derived sulphur compounds +; raphides often 0, styloids +; laticifers +; leaves (spiral), sheath closed, long, shortly ligulate [Allium, at least]; flowers medium sized; T ± connate; A connate or adnate to free; (stigma wet); style solid; ovules 2-many carpel, in two ranks, campylotropous (anatropous), (micropyle bistomal), nucellar cap + (?0), obturator +; seeds angular, exotestal, other layers of testa collapsed or not; (endosperm pitted); chromosomes 2-20 µm long; (cotyledon not photosynthetic).
13[list]/795. Mainly South America, but Allium esp. N. Temperate Eurasia - three groups below. [Photo - Collection] [Photo - Inflorescence, Flower, Flower.]
2A. Allieae Dumortier
Bulbs lacking starch; vessel elements in roots often with simple perforation plates; leaves ± unifacial; T basally connate, (one-nerved), corona 0; A both basally connate and adnate to C, filaments often winged, tapetal cells uninuclear; (G semi-inferior), style ± gynobasic, (paired projections from the ovary); ovules 2-14/carpel, epitropous; (seed with caruncle); endosperm cellular, embryo long, curved; n = (7) 8 (9-11), chromosomes 9.0-19.3 µm long, human-type telomeric repeats lost.
1/260-780. North temperate, often seasonally dry, especially the Mediterranean to Central Asia, west North America, scattered in Africa (map: from Hultén 1962; de Wilde-Duyfjes 1976; Hanelt 1990; Hanelt et al. 1992; Fl. N. Am. 26: 2002, not native in Iceland).
Synonymy: Alliaceae Borkhausen, nom. cons., Cepaceae Salisbury, Milulaceae Traub
[Tulbaghieae + Gilliesieae]: bulbs with starch; endosperm helobial.
2B. Tulbaghieae Meisner
Plant often rhizomatous; leaf sheath short; flowers bracteate; T rather strongly connate, corona massive, lobes connate or not; A sessile, adnate to corolla tube and/or corona; ovules 2-several/carpel; seeds ± flattened; embryo?; n = 6, chromosomes 11.5-14.7 µm long.
1/22. Southern Africa (map: from Vosa 1975; Trop. Afr. Fl. Pl. Ecol. Distr. 7. 2012).
Synonymy: Tulbaghiaceae Salisbury
2C. Gilliesieae Baker
Corona +/0, (A 2-3; variously connate and adnate; extrorse), (staminodes +); ovules 2-many/carpel, style solid [Nothoscordum]; (ovule with inner integument 5-7 cells across - Dichelostemma); embryo short; n = ³4.
10/80: Nothoscordum (22). South U.S.A., Mexico to South America (map: from Fl. N. Am. 26. 2002).
Synonymy: Gilliesiaceae Lindley
Evolution. Divergence & Distribution. Nguyen et al. (2008) found that Old and New Word species of Allium are mostly in two separate clades, although basal to the clade containing all North American members (in subgenus Amerallium) are Eurasian taxa. Diversity within North America Allium is centered in the west, especially in California, and a number of species there are serpentine endemics (Nguyen et al. 2008).
Pollination Biology & Seed Dispersal. Gilliesia has very strongly monosymmetric flowers with only two stamens; the flowers may mimic insects (Rudall et al. 2002).
Chemistry, Morphology, etc. The apparently bifacial leaves of at least some species of Allium have inverted vascular bundles along the adaxial surface and vascular bundles with normal orientation along the abaxial surface (Mathew 1996).
In Gilliesieae, Schickendantziella has only three tepals; they are caudate. The flowers of Allium are shown with the median member of the outer whorl in the adaxial position (Spichiger et al. 2004). Do Alliodeae have apotropous ovules? There has been major movement of ribosomal protein and succinate dehydrogenase genes from the mitochondrion in Allium (Adams & Palmer 2003), and that genus has also lost its minisatellite telomeres (Sýkorová et al. 2006a).
Some information is taken from Berg (1996) and Berg and Maze (1966), both embryology, and Rahn (1998: general). For Allium, see Rabinowitch and Currah (2002: more horti-/agricultural), Fritsch and Friesen (2002 [and many other papers in same book]: general), Fritsch and Keusgen (2006: cysteine sulphoxide distribution), and Choi et al. (2011: floral development, esp. epidermis).
Phylogeny. Fay and Chase (1996) discuss relationships within the subfamily; the topology is [Allieae [Tulbaghieae + Gilliesieae]], although the support for the clades is rather weak. Fay et al. (2006b) found that part of Ipheion was embedded in Nothoscordum. Nguyen et al. (2008) provide a phylogeny for Allium (see also Friesen et al. 2006; Hirschegger et al. 2010: section Allium; Choi et al. 2012: North American species; Li et al. 2012: subgenus Amerallium); the relationships of members of the small subgenera Nectaroscordum and Microscordum are unclear (Nguyen et al. 2008). In the large subgenus Melanocrommyum of Allium there seems to be extended incomplete lineage sorting, and morphological sections are not supported by molecular data (Gurushidze et al. 2008, esp. 2010).
Classification. See Fay and Chase (1996) as Alliaceae. Friesen et al. (2006) provide a subgeneric and sectional classification of Allium; Gregory et al. (1998) list names included in it. See Vosa (1975) for a revision of Tulbaghia and details of its cytology.
3. Amaryllidoideae Burnett Back to Asparagales
Norbelladine alkaloids, non-protein amino acids, chelidonic acid +, saponins 0; exodermis with long and short cells, 2-4-layered velamen; sclerechymatous ring in scape, bundles in rings; petiole bundles in arc; (lacunae formed by breakdown of parenchyma); leaves (spiral), vernation flat or revolute to involute, (vascular bundles inverted; base sheathing); bracts equitant; flowers large, (monosymmetric, with median member of outer tepalline whorl adaxial; T ± free, corona +/0 [morphology various]; anther middle layer of wall from outer secondary parietal cells; ovary inferior, stigma capitate to deeply trifid, (wet); (ovule with outer integument ³3 cells across); endosperm starchy or with hemicellulose (thin-walled), embryo poorly differentiated, small; n = (5-)11(12<), chromosomes (1.5-)3-28 µm long; cotyledon bifacial, (not photosynthetic), primary root well developed, contractile.
59[list]/800+ - fourteen groups below. Tropical (temperate), esp. South America and Africa, also Mediterranean (map: from Allan Meerow and O. Seberg, pers. comm.; Snijman 1984; Fl. N. Am. 26: 2002; de Castro et al. 2012). [Photo - Flower, Fruit.]
3A. Amaryllideae Dumortier
Stomata paracytic, subsidiary cells with oblique divisions; extensible [helically-thickened] fibres in leaf; leaves follow the flowers, (perennial - many Crininae); corona of webbing joining filaments basally, or small appendages developed from filaments, or 0 [Crineae]; pollen bisulcate, exine gemmate, with scattered spinules, intectate-columellate; (style laterally displaced); ovules unitegmic; embryo sac bisporic and 8-celled [Allium type]; seeds water-rich, non-dormant, phytomelan 0, testa to 25 cells thick, chlorophyllous, with stomata, or ± collapsed, or 0; endosperm usu. with a corky layer, chlorophyllous, starchy, embryo chlorophyllous; (n = 10, 12, 15), chromosomes 5.3-20.5 µm long.
11/146: Crinum (65), Strumaria (23). SubSaharan, especially South Africa, Crinum Pantropical.
Synonymy: Crinaceae Vest, Strumariaceae Salisbury
Calostemmateae, etc.: bundle sheath cells parenchymatous.
[ Calostemmateae[Cyrtantheae + Haemantheae]]: ?
3B. Calostemmateae D. & U. Müller-Doblies
Ovules 2-3/carpel; embryo germinates precociously producing a bulbil; fruit dry, indehiscent; phytomelan 0; n = 10, chromosomes 3.3-8 µm long.
2/4. Australia, Malesia.
[Cyrtantheae + Haemantheae]: fruit indehiscent.
3C. Cyrtantheae Traub
Scape lacking sclerenchymatous ring, subepidermal collenchyma +; 1-layered rhizodermis +, velamen 0; seeds flat, winged, horizontally stacked, phytomelan +; n = (7) 8 (11).
1/50 (Cyrtanthus). Africa, especially the south.
Synonymy: Cyrtanthaceae Salisbury
3D. Haemantheae Hutchinson
(Plant rhizomatous); (alkaloids 0 - Gethyllis); 1-layered rhizodermis +, velamen 0; scape lacking sclerenchymatous ring, subepidermal collenchyma +; inflorescence bracts connate, (flowers single - Gethyllis, etc.); (A 12); fruit baccate; seeds angled, etc.; phytomelan 0 (+); n = 6, 8, 9, 11, 12; chromosomes 3.0-24 µm long.
6/80: Gethyllis (32), Haemanthus (22). Tropical Africa, mostly in the South.
Synonymy: Gethyllidaceae Rafinesque, Haemanthaceae Salisbury
[Lycoridae [Galantheae, Pancratieae, Narcisseae]] / Eurasian Clade: seeds subglobose, turgid.
3E. Lycoridae D. & U. Müller-Doblies
(Seeds irregularly discoid - Ungernia); n = 11 (etc.).
2/26: Lycoris (20). Temperate to subtropical East Asia to Iran.
[Galantheae, Pancratieae, Narcisseae]: ?
3F. Galantheae Parlatore
(Inflorescence bractes connate along one side); (anthers dehiscing by pores); elaiosome + (0); n = 7-9, 11, 12.
8/31: Galanthus (17). Europe to N. Africa, the Crimea and the Caucasus.
Synonymy: Galanthaceae G. Meyer, Leucojaceae Borkhausen
3G. Pancratieae Dumortier
Staminal tube toothed; n = 11, chromosomes 8.7-22 µm long.
1/20. Mediterranean, southern Asia, to sub-Saharan Africa.
Synonymy: Pancratiaceae Horaninow
3H. Narcisseae Lamarck & de Candolle
Inflorescence bracts basally connate; (corona + - Narcissus); elaiosome + (0); n = (7) 11 (13), etc.
2/58: Narcissus (50). Europe to W. Asia and N. Africa.
Synonymy: Narcissaceae Jussieu
[Hippeastreae [Eustephieae [Hymenocallideae, Stenomesseae, Eucharideae]]] / Andean + Extra-Andean/American Clade: 1-layered rhizodermis +, velamen 0; scape lacking sclerenchymatous ring, subepidermal collenchyma +; bracts obvolute; (seeds flat, horizontally stacked), phytomelan common.
3I. Hippeastreae Sweet
Inflorescence bracts often connate basally (along one side); flowers (very strongly) monosymmetric; (corona +); A declinate, of varying lengths; seeds flattened, winged or D-shaped; n = 8-13, 17, etc., chromosomes 3-16.7 µm long.
11/218: Hippeastrum (55, the "Amaryllis" of many a windowsill), Zephyranthes (50), Habranthus (50). S.E./S.W. U.S.A., the Caribbean, and Central and South America.
Synonymy: Brunsvigiaceae Horaninow, Oporanthaceae Salisbury, Zephyranthaceae Salisbury
[Eustephieae [Hymenocallideae, Stenomesseae, Eucharideae]] / Andean Tetraploid Clade: palisade leaf mesophyll absent; flowers polysymmetric; x = 23 [tetraploid].
3J. Eustephieae Hutchinson
A of two lengths; seeds flattened, winged; (n = 21, etc.).
3/15: C. Andes (Peru, Bolivia, Argentina).
[Hymenocallideae, Stenomesseae, Eucharideae]: ?
3K. Hymenocallideae Small
Pollen grains with the ends narrowed, with different sculpture [auriculate]; testa thick, spongy, chlorophyllous, vascularized, phytomelan 0 (+ - Leptochiton); embryo starchy; (n = 19, 20, 22), chromosomes 4-11.8 µm long.
3/65: Hymenocallis (50). S.E. U.S.A., the Antilles, Central America to Bolivia.
3L. Stenomesseae Traub
(Velamen + - Pamianthe); leaves petiolate, strap-shaped; staminal cup + (0); seeds flattened, obliquely winged.
8/62: Stenomesson (35). Andean South America S. to Bolivia, Costa Rica (1 sp.).
3M. Eucharidae Hutchinson
Leaves petiolate, elliptic; (flowers monosymmetric); seeds globose, turgid, coat lustrous; chromosomes 2.3-10.7 µm long.
4/28: Eucharis (17). Central America, the Andes S. to Bolivia.
Evolution. Divergence & Distribution. Meerow (2010) discussed diversification in American Amaryllidaceae in terms of the interplay of canalization and genome doubling, emphasizing the floral and vegetative diversity encompassed by the Andean tetraploid-derived clade. Santos-Gally et al. (2012) discussed the biogeography of the Mediterranean-centred Narcissus
Ecology & Physiology. Amaryllidoideae are an important component of the distinctive Cape geophytic flora (Procheŝ et al. 2006) having about 100 species endemic there. For water-catching leaves with very distinctive morphologies that are found especially in taxa from Namaqualand, see Vogel and Müller-Doblies (2011).
Floral Biology & Seed Dispersal. Monosymmetry is said to be ancestral in the subfamily (Meerow & Snijman 1998; Meerow 2010); it is certainly very labile, reversals and parallelisms being common, and it is perhaps under simple genetic control (Meerow et al. 1999). Some kind of corona is common, but its morphological nature varies (see below). The flowers are protandrous. A number of species of Amarayllis are heterostylous (Santos-Gally 2013 and references)
Almost three hundred species in the subfamily have myrmecochorous seeds (Lengyel et al. 2010). Wind dispersal of the seed is common in Amaryllideae, the rigid, radiating pedicels allowing the infructescences to bowl along in the wind. The testa is commonly massive, green and photosynthetic, and with anomocytic stomata in Amaryllidinae, while in Crinum, of the same tribe, it is the endosperm that is green and photosynthetic. Seeds of some species of Crinum lack a testa and may have a corky outer endosperm; such seeds can float and remain viable in sea water for up to two years, while seeds of other species lack the corky layer, sink fast and can germinate without very much in the way of water at all (Snijman & Linder 1996; Bjorå et al. 2006). In Boophone and Cybistetes the seeds germinate while still in the fruit, and in Calostemmateae the bulbil, a precociously-germinated embryo, is the dispersal unit. The inflorescence of Gethyllis (Haemantheae, includes Apodolirion) has a single flower; the ovary is subterranean and the many-seeded fruit is indehiscent and may be sweetly scented when ripe; dispersal by small mammals?
Chemistry, Morphology, etc. Norbelladine alkaloids, unique to Amaryllidoideae, are tyrosine derivatives. There are over 200 different structures of which 79 or more are found in Narcissus alone (Martin 1987; Bastida & Viladomat 2002: other references in the same volume; Rønsted et al. 2008b. These alkaloids cause acetylcholinesterase inhibition, etc., in Hameantheae (Bay-Smidt et al. 2011) and Calostemmateae (Jensen et al. 2011). All told over 500 alkaloids placed in 118 different classes have been recorded from the subfamily (Rønsted et al. 2012); a number of species are poisonous because of them.
Because of the leaf fibres in Amaryllideae, the coverings of the bulbs produce highly-extensible cotton-like fibres when torn. There are often crystals of calcium oxalate in the epidermis. Petiolate leaves have evolved at least six times in the family.
The flowers of Galanthus are shown with the median member of the outer whorl in the adaxial position (Spichiger et al. 2004), see also the similar position in Hippeastrum and several other monosymmetric Amaryllidoideae. Some species of Phaedranassa have slit-monosymmetric flowers, with all the stamens, etc., leaving the flower via an abaxial slit in the perianth tube; I do not know details of the symmetry there. Flowers of some species of Crinum are monosymmetric. In Galanthus in particular the inner whorl of tepals is very different from the outer whorl, although both are petal-like.
The corona of e.g. Hymenocallis, evascularized outgrowths of the filaments, and that of Narcissus, vascularized and tubular (see also Scotland 2013), but not associated with the stamens, are quite different (e.g. Arber 1937); the corona may also be a tube, sometimes toothed (Pancratium), on which the stamens are born. Haemanthus has tepals with a single trace. In Strumaria and Carpolyza the bases of the filaments are adnate to the style, while in Strumaria and Tedingia the base of the style may be much inflated, even bulbous. Flowers of Gethyllis have up to 18 stamens. It is unclear if some ovules are ategmic. Crinum has cellular endosperm. In Hymenocallis caribaea the ovule is crassinucellate ("pseudocrassincellate"), the micropyle is zig-zag, and the vascularized outer integument is massive (Raymúndez et al. 2008). x = 11 may be the basal chromosome number for the family (Meerow et al. 2006). A very long-tubular dropper cotyledon sheath may develop during germination.
For anatomy, see Arroyo and Cutler (1984), for pollen, see Dönmez and Isik (2008), and for general information, see Meerow and Snijman (1998).
Phylogeny. Phylogenetic relationships within Amaryllidoideae are [Amaryllideae [Cyrtantheae [Calostemmateae, Haemantheae, Gethyllideae [Eurasian Clade [Andean Clade, Extra-Andean Clade]]]]] (Meerow et al. 1999, 2000a, 2000b). Relationships between major clades of American and some southern African members are not well understood, furthermore, Meerow et al. (2006) found that the inclusion of Hannonia, Lapiedra and Vagaria destabilised relationships in the European clade; Lledó et al. (2004) included the last two in Galantheae. Meerow and Clayton (2004) discussed relationships among African taxa. In a more recent study using genes from all three compartments and sampling 108 species recovered the relationships [Amaryllideae [[Calostemmateae [Cyrtantheae + Haemantheae]] [Eurasian Clade [Andean Clade, Extra-Andean Clade]]]], although support for some nodes was poor; Gethyllis was embedded in Haemantheae (Rønsted et al. 2012: see classification above).
For a phylogeny of Cyrtanthus and discussion on its evolution, see Snijman and Meerow (2010); molecules and cytology, but less so morphology, tend to agree. Meerow and Snijman (2001, see also 2006) discuss relationships within Amaryllideae; Amaryllis and Boophone are successively sister to the rest of the tribe. Amaryllis differs from other Amaryllidineae in not having a green testa, etc. Meerow et al. (2003) outline the phylogeny of Crinum, the only pantropical member of Amaryllidaceae; see also Kwembeya et al. (2007).
For relationships in Haemantheae, see Conrad et al. (2006) and Bay-Smidt et al. (2011). Meerow et al. (2006) provide a phylogeny for the Eurasian Clade, which includes daffodills, snowdrops, etc. The main dichotomy separates the Central and East Asian Lycorideae from the rest, which centre on the Mediterranean region. ITS and ndhF phylogenies are not congruent (Meerow & Snijman 2006). For a phylogeny of Galantheae and its alkaloids, see Lledó et al. (2004) and Larsen et al. (2010), and for that of Narcissus, see Rønsted et al. (2008b: acetylcholinesterase-inhibiting alkaloids) and Santos-Gally (2012).
Within Hippeastreae, Worsleya and Griffinia are morphologically and phylogenetically isolated - n = 10, 21; velamen + [Worsleya]; flowers blue; seeds whitish, globose, turgid [Griffinia] (Meerow et al. 2000a).
Classification. For the infrafamilial classification of Amaryllidaceae, I follow Chase et al. (2009). For a classification of Amaryllideae, see Meerow and Snijman (2001, 2006), and for generic limits in Galantheae, see Lledó et al. (2004).
ASPARAGACEAE Jussieu, nom. cons. Back to Asparagales
153/2500. World-wide, but not Arctic - seven groups below.
Age. Divergence within the crown group began ca 89 m.y.a. (Janssen & Bremer 2004). Eguiarte (1995), however, suggested that Agavaceae-Nolinaceae - the two are members of the two main clades here - diverged only some ca 47 m.y.a., while Bell et al. (2010) suggested a crown-group age of (66-)56, 51(-42) m.y..
Evolution. Divergence & Distribution. There are no obvious apomorphies for Asparagaceae s.l., however, "endosperm helobial, thick-walled, pitted, hemicellulosic" might be placed at this level. The homoisoflavanones found in Scilloideae are rather uncommon in flowering plants, but they are also found in Camassia (Agavoideae, ex Chlorogaloideae) and Ophiopogon (Nolinoideae).
Phylogeny. These seven subfamilies form a rather well supported clade in Fay et al. (2000). Fay et al. (2000), Pires et al. (2001), and Pires and Sytsma (2002) discuss uncertainties as to the immediate sister taxon to Themidaceae (= Brodiaeoideae). Aphyllanthes has a very long branch in the three-gene analysis of Fay et al. (2000), and its phylogenetic position is unclear; its removal from analyses can rather dramatically changes support values (Chase et al. 2006). A position close to Hyacinthaceae (= Scilloideae) was found by McPherson and Graham (2001), but Pires et al. (2006) place it sister to Laxmanniaceae (= Lomandroideae), albeit with weak support. [Themidaceae + Hyacinthaceae] appear a moderately well supported clade in Fay and Chase (1996) and Meerow et al. (2000), but support in the two-gene analysis of Jang and Pfosser (2002: Aphyllanthes not included) is only weak (see also Chase et al. 2006; Pires et al. 2006). Seberg et al. (2012) found the relationships [[Brodiaeoideae + Scilloideae] [Aphyllanthoideae + Agavoideae]], but the position of Aphyllanthes had no support. Steele et al. (2012) also found Aphyllanthes associating with this group, but again with little support; there was good support for a clade [Lomandroideae [Asparagoideae + Nolinoideae]] (for this latter clade, see also Fay et al. 2000: moderate support; Seberg et al. 2012, strong support). For details of relationships, see also Bogler et al. (2006).
Classification. This is a highly unsatisfactory family. Nothing characterises it, and while some of the subfamilies have several distinctive apomorphies and are also easy to recognise, others are difficult to recognise. The flowers of the whole group are for the most part a rather undistinguished "lily"-type, and quite often are rather small. Asparagoideae, and especially Nolinoideae and Agavoideae, are very heterogeneous, several families having been segregated from them in the past. For the use of Asparagaceae s.l. to refer to the entire clade, c.f. A.P.G. II (2003) and A.P.G. III (2009). The subfamilial classification follows that in Chase et al. (2009b), but I have also included familial names for each clade, in part because the roots of the two sets of names differ in over half the cases and both will be encountered in the literature.
[Aphyllanthoideae [Agavoideae [Brodiaeoideae + Scilloideae]]: ?
1. Aphyllanthoideae Lindley Back to Asparagales
Flavonols +; vessel elements in roots often with simple perforation plates; secondary growth +; stems alone photosynthetic, with parallel wax scales; leaves two-ranked, vernation supervolute-subinvolute, scaly, non-photosynthetic, ligulate, base?; inflorescence scapose, flowers multibracteolate, sessile; T marcescent, basically free; A adnate to base of T; pollen spiraperturate; ovary sulcate down middle of loculus; infra-locular septal nectaries +, stigma trifid, dry; ovule 1/carpel, micropyle?; seeds slightly flattened, exotestal cells large, isodiametric; endosperm ?, 0; n = 16; cotyledon photosynthetic, terete, first leaf terete.
1[list]/1: Aphyllanthes monspeliensis. W. Mediterranean. [Photo - Flower © E. Bourneuf.]
Chemistry, Morphology, etc. The stomata are in bands down the scape. The tepals have but a single bundle. Is there chelidonic acid?
General information is taken from Conran (1998); he mentions helobial endosperm development here, but c.f. Schnarf and Wunderlich (1939), apparently the only source of embryological information.
Synonymy: Aphyllanthaceae Burnett
[Agavoideae [Brodiaeoideae + Scilloideae]]: ?
Age. The age of this node is estimated at (62-)51, 46(-37) m.y. by Bell et al. (2010).
2. Agavoideae Herbert Back to Asparagales
Plant rhizomatous; endosperm helobial, thick-walled, pitted, hemicellulosic.
23/637 [list] - five groups below. More or less world-wide, esp. S.W. North America, few in Malesia, N. Australia, not cold temperate, New Zealand, etc. (map: see Ying et al. 1993; García-Mendoza & Galván V. 1995; Fl. N. Am. 26: 2002; Seberg 2007).
Leaves ?spiral, base?; inflorescence subspicate, branched; T ± free; A 3, opposite and adnate to middle of inner T; ovules 2/carpel, apotropous; seeds angled; embryo curved; n = 11; hypocotyl 0.
1/1: Anemarrhena asphodeloides. N. China, Korea.
Synonymy: Anemarrhenaceae Conran, M. W. Chase & Rudall
[[Agave, etc. + Hesperocallis] [Behnia [Herreria, etc. + Anthericum, etc.]]]: (vessels in stem); nucellar cap, hypostase +.
Age. The age of this node is some (48-)40, 33(-23) m.y. (Bell et al. 2010) or 36-35 m.y.a. (Wikström et al. 2001).
This group has 100% support in three- and four-gene trees (Chase et al. 2000a; Fay et al. 2000; Bogler et al. 2006).
4B. Agave, etc. + Hesperocallis
Also caulescent, (bulbs, tunicated or not), leaves often fleshy; non-protein amino acids, saponins, (homoisoflavanones - Chlorogalum), flavonols +; stem secondary growth +; adaxial bundles in leaf inverted [?level]; also styloids +; (stomata para- or tetracytic), cuticular wax rodlets parallel; leaves spiral, (petiolate; vascular bundles inverted; margins serrate), apex (pungent-)pointed, base ?; inflorescence usually branched, and/or flowers in pairs or fascicles, (pedicel articulated - Chlorogalum, etc.); flowers large, (monosymmetric); tapetal cells several-nucleate; pollen semitectate, (operculate); ovary superior to inferior, (styles +; with 3 canals - Camassia), stigma wet to dry; ovules many/carpel, outer integument (4-)9-14 cells across, parietal tissue absent-2 cells across, (nucellar cap 2 cells across), ± postament, hypostase, obturator +; (capsule septicidal - some Yucca), (fruit a berry), T marcescent; seeds flattened [?all]; (endosperm thin-walled - Hosta), (perisperm +, oily - Yucca, Agave); n = 24, 30, chromosomes 0.4-10 µm long, bimodal; genome duplication; (cotyledon non-photosynthetic - Funkia), hypocotyl to 4 mm long, collar rhizoids +, primary root often branched.
10/340: Agave (210), Yucca (50). Central U.S.A. to N. South America, mostly S.W. North America, also East Asia (Hosta). [Photo - Flower]
Synonymy: Agavaceae Dumortier, nom. cons., Chlorogalaceae Doweld & Reveal, Funkiaceae Horaninov, nom. illeg., Hesperocallidaceae Traub, Hostaceae B. Mathew, Yuccaceae J. Agardh
[Behnia [Herreria, etc. + Anthericum, etc.]]: ?
Age. The age of this node is some (34-)24, 22(-13) m.y. (Bell et al. (010).
± Ssprawling, rhizomatous; secondary thickening +; tannin cells 0; velamen 1-layered; vessel elements also in the stem; leaves two-ranked, "supervolute", petiolate, blade broad, with midrib and transverse tertiaries, leaf base not sheathing; dioecious; A adnate to base of T; ovules 2-3/carpel, micropyle?, parietal tissue absent; stigma 3-lobed, wet; fruit a berry, T marcescent, not twisting; seeds angular, phytomelan 0, testa and tegmen thin-walled; endosperm walls not pitted and hemicellulosic; n = ?
1/1: Behnia reticulata. Zimbabwe to eastern South Africa.
Synonymy: Behniaceae Conran, M. W. Chase & Rudall
[Herreria, etc. + Anthericum, etc.]: (stem secondary growth +).
4E. Herreria, Herreriopsis
Usu. climbers, prickly; saponins +, chelidonic acid?; (vessel elements in stem); mucilage cells 0; cuticular wax rodlets parallel; leaves spiral, fasciculate, sheath?; pedicels not articulated; T and A free; ovules 1-many/carpel, parietal tissue?; fruit a septicidal capsule; seeds flattened; "embryo short"; n = 27, dimorphic [one large], chromosomes 0.7-3.7 µm long [Herreria]; "germination epigeal".
2[list]/9. South America (Brazil southwards), Madagascar. [Photo - Fruit.]
Synonymy: Herreriaceae Kunth
5. Anthericum, etc.
Rhizome short; chelidonic acid +; (velamen +); (vessel elements in the stems); mucilage cells +, tannin cells 0, (styloids + - Chlorophytum); cuticular wax rodlets parallel; leaves spiral to two-ranked, base sheathing; inflorescence thyrsoid (raceme); (pedicels not articulated); (flower monosymmetric), (T tube 0); (pollen mixed with raphides); stigma dry; ovules 2-many/carpel, outer integument ca 4 cells across; embryo sac haustoria common; T persistent in fruit; seeds angular or flattened, tegmen?; embryo curved or angled; n = 7, 8, 10, 11, 13-15, etc., chromosomes 2-10(-13.8) µm long, genome duplication [Chlorophytum]; cotyledon not photosynthetic, coleoptile + [Chlorophytum].
8/285: Chlorophytum (150), Anthericum (65), Echeandia (60). More or less worldwide, but not cold temperate, few in Malesia, N. Australia, not New Zealand, etc. [Photo - Inflorescence, Flower.]
Synonymy: Anthericaceae J. Agardh
Evolution. Divergence & Distribution. Good-Avila et al. (2006) suggest that Agave et al. are only some 26-20 m.y. old, and Yucca 18-13 m.y. old. Rocha et al. (2006) suggest ca 12.75 m.y. as the age of Agave etc. and ca 10.2 m.y. for Agave s.l. (Hesperaloe and everything above in the tree - Bogler et al. 2006; c.f. also Smith et al. 2008); there are yet other possibilities for dates.
Good-Avila et al. (2006) discussed diversification in both Agave, which they suggest may be connected with the adoption of bat-pollination, and Yucca (see also Rocha et al. 2006). Smith et al. (2008) suggested that diversification was not significantly different in Yucca, with its 34 species, and Agave, with some 240 species, and there was little evidence that the adoption by Yucca of its remarkable pollination mechanism increased its diversification rate. Pulses of diversification in agaves may have happened a mere 9-6 m.y.a., a time when other succulent clades were diversifying (e.g. Good-Avila et al. 2006; Arakaki et al. 2011).
Pollination Biology & Seed Dispersal. The Yucca-yucca moth (Tegeticula, Prodoxidae) association has hitherto been a textbook example of mutualism or co-evolution, two groups showing reciprocal evolutionary change (see Althoff et al. 2012 for more details). The association may be some 40 m.y. old (c.f. the dates above, Pellmyr et al. 1996, 2007; Pellmyr & Leebens-Mack 1999; Pellmyr 2003; Gaunt & Miles 2002; Althoff et al. 2006); there may have been another and more recent radiation of yucca moths only 3-2 m.y.a.. Close relatives of yucca moths also eat Dasylirion and Nolina (Nolinoideae, this page) and other Prodoxidae are found on Saxifragaceae (Saxifragales); the ancestral condition for yucca moths may have been to eat ovaries (Yoder et al. 2010). Prodoxus, not a pollinator but a specialist herbivore on Yucca, and Parategeticula, another pollinator, are also involved. Much of the divergence in Yucca seems to have occurred before that of its main pollinator but only a mere 6-4 m.y.a., and given the vagility of the moth, it is difficult to imagine how co-evolution might work. Initial diversification in Yucca may have been in association with Parategeticula, a poor flier and now rather uncommon (Althoff et al. 2012).
Ecology & Physiology. Nobel (1988) discussed the eco-physiology of agaves and their relatives. Over 300 species are succulents, mostly leaf succulents (Nyffeler & Eggli 2010b).
Genes & Genomes. For the connection between the evolution of the bimodal karyotype of Agave and its close relatives and polyploidy, see McKain et al. (2011, esp. 2012); Hesperocallis has 4 long, 2 medium and 18 short chromosomes, the other genera have 5 long and 25 short chromosomes.
Chemistry, Morphology, etc. The raphides of Agave are hexagonal in transverse section. The leaves of Herreria and Herreriopsis are described as being cladode-like (Conran 1998) or cladodes (Stevenson in Takhtajan 1997).
The flowers of Agave are shown with the median member of the outer whorl in the adaxial position (Spichiger et al. 2004). Camassia at least has single-trace tepals, Agave, etc. have three, while Hosta may have as many as 13 (Lin et al. 2011). The outer tepals of Herreriopsis have sac-like bases - possibly tepalline nectaries. The tapetal cells of Polianthes (= Agave) are multinucleate. In Hosta the stamens are sometimes inserted on the ovary. Germination of the pollen grain via the proximal pole has been reported in Beschorneria (Hesse et al. 2009a). Furcraea has nuclear endosperm.
Traub (1982) noted that Hesperocallis undulata smells of onions, and he even associated it with his Alliales. The genus was geographically odd in Hostaceae s. str., which is where other workers had placed it (c.f. Kubitzki 1998b), but not in Agavoideae as here circumscribed; now Hosta is a little odd from the geographical point of view.
The ovary and fruit of Leucocrinum (Anthericum group) are below the surface of the ground (Bogler et al. 2006). At least some mitochondrial genes show an accelerated rate of change (G. Petersen et al. 2006). Some information is taken from Conran (1998); ovule morphology is known from Leucocrinum alone in the Anthericum group.
Ubisch bodies are present in Anemarrhena, so there is probably a glandular tapetum. Information is taken from Conran and Rudall (1998 - confusion over stamen position) and Rudall et al. (1998b). For information about Behnia, Herreria and Herreriopsis, see Conran (1998); details of ovules/embryology are unknown.
See Judd et al. (2007) for general information; for additional information, especially the part that has been considered Agavaceae s. str. in the past, i.e. Agave, Yucca and their immediate relatives, see Alvarez & Köhler (1987: pollen), Fagerlind (1941b), Cave (1948, 1955), Wunderlich (1950: also floral morphology), and di Fulvio and Cave (1965), all embryology, and Verhoek (1998: general): genome duplication); see also Kubitzki (1998b - Hostaceae), Speta (1998 - Hyacinthaceae - Chlorogaloideae).
Phylogeny. For relationships within this clade, see Pires et al. (2004) and especially Bogler et al. (2006: 2- and 3-gene analyses, the latter with missing data, but overall the same topology). I have followed the latter - which see for more details - in the topology above. Support for the subfamily as a whole is only 75%, that for the [Behnia + Herreria, etc. + Anthericum, etc.] clade 87%, and that for [Herreria, etc. + Anthericum, etc.] only 51% (and still less in the two-gene tree); however, other nodes have close to 100% support, and there is a fair amount of detail resolved in relationships around Agave and Yucca (see below). Largely similar relationships were found by G. Petersen et al. (2006c) in their analysis of variation of four mitochondrial genes that are evolving particularly quickly in this clade.
The circumscription of group 4b above, Agave etc., corresponds to that of Agavaceae s.l. in Bogler et al. (2006). Genera like Camassia, etc. (ex Hyacinthaceae-Chlorogaloideae) are included, and these latter taxa have rhexigenetic lacumae (Lynch et al. 2006) like many Hyacinthaceae (= Scilloideae). Hesperocallis undulata is sister to the rest of the Agave, etc., clade (Bogler et al. 2006). Smith et al. (2008) included Hosta, etc., in their Agavaceae and excluded Anthericaceae, although support for Agavaceae so delimited was weak; that for the still broader circumscription adopted here was stronger. For other phylogenetic work on this group, see also Eguiarte et al. (1994), Bogler and Simpson (1996: molecular) and Sandoval (1995: morphological).
Classification. The broad concept of Agavoideae adopted here may not seem very satisfactory, but none of the alternative solutions is any better. Agave should probably include Polianthes, Manfreda, etc., see e.g. Bogler and Simpson (1995), Bogler et al. (2006) and Rocha et al. (2006).
Previous Relationships. Paradisea (ex Asphodelaceae/Xanthorrhoeaceae-Asphodeloideae) is a member of the Anthericum group (e.g. Chase et al. 2000b). Behnia was included in Luzuriagaceae (Liliales here) by Taktajan (1997), but it has also been placed in other lilialean and asparagalean families (Bogler et al. 2006).
[Brodiaeoideae + Scilloideae]: steroidal saponins +; leaves spiral; inflorescence scapose, pedicels bracteate; raphides in carpel wall; ovules anatropous; endosperm helobial or nuclear; cotyledon not photosynthetic.
Age. The age of this node is estimated at (56-)45, 40(-15) m.y. by Bell et al. (2010).
Evolution. Divergence & Distribution. For some other characters of this pair, see Fay and Chase (1996); laticifer-like structures may occur in both.
3. Brodiaeoideae Traub Back to Asparagales
Plant monopodial, cormose, storing starch; sheath fibrous; ; laticifers +; mucilage cells?; leaves (unifacial - Brodiaea), sheath closed; inflorescence umbellate, cymose, inflorescence bracts several, scarious, also internal bracts; pedicels often articulated; (T free; corona +); A (3), connate and/or adnate to T, (filaments flattened); (ovary stipitate, adnate to T by flanges opposite the outer tepals), stigma capitate to trifid, dry (wet - Bloomeria); ovule with outer integument 3-4 cells across, (inner integument 3+ layers across), parietal tissue 3-4 cells across, (nucellar cap +); seeds angular, cells of tegmen much enlarged (not - Triteleia); (endosperm helobial - Muilla, Triteleia), "embryo short"; n = 5-12+; hypocotyl?, primary root persistent.
12[list]/62. S.W. North America, to British Columbia and Guatemala (map: see Moore 1953; Fl. N. Am. 26: 2002). [Photo - Flower, Flower, Fruit.]
Chemistry, Morphology, etc. Little is known about the chemistry of Brodiaeoideae. When the tepalline tube is adnate to the stipitate gynoecium, three narrow, ?nectar-containing tubes are formed. Embryologically Brodiaeoideae are quite variable. The inner integument is massive or not, ditto base of the nucellus, endosperm development varies, etc. (Berg 2003 for a summary).
Information is taken from Moore 1953 (morphology), Berg (1978: embryology), Rahn (1998: general).
Phylogeny. There are two major clades, [Muilla, Triteleia] and [Dipterostemon, Dichelostemma, Brodiaea], albeit with only moderate support. The first clade has a long tepalline tube and the second has appendages on the bases of the filaments that form a nectar cup; both characters arise in parallel in the opposing clade (Pires & Sytsma 2002; c.f. Seberg et al. 2012). See also Pires et al. (2001) for phylogeny and morphological evolution.
Previous Relationships. Themidaceae/Brodiaeoideae have often been included in Alliaceae/Amaryllidaceae-Allioideae because of their superficially similar umbellate inflorescence and rather undistinguished monocot flowers (e.g. Takhtajan 1997).
Synonymy: Themidaceae Salisbury
4. Scilloideae Burnett Back to Asparagales
Plant bulbous, geophytic, roots often contractile; polyhydroxyalkaloids, homoisoflavones, flavone C-glycosides +; little sclerenchyma in the leaf (well-developed); mucilage cells +; (leaf waxes with parallel platelets); bulb leaf sheaths closed or not; inflorescence scapose [?all], (branched), (spike), pedicels not articulated, bracteole 0; (corona +); stigma capitate to punctate and papillate; ovules 1-many/carpel, outer integument 2-3 cells across, parietal tissue usu. 2-4 cells across, (nucellar epidermis radially elongated), nucellar cap +/0, raphides +, obturator +; (postament +); seeds black; testa multi-layered; chromosomes 1.2-18 µm long; nucleus with protein crystals; (hypocotyl 0; collar rhizoids +).
41-70[list]/800-1025 - six groupings below. Predominantly Old World, Mediterranean climates, esp. S. Africa and the Mediterranean, to Central Asia and Japan; a few in South America (map: both colours).
Age. Oziroë diverged from the rest of the clade in the Oligocene ca 28 m.y.a. (Ali et al. 2012).
3A. Oziroëeae M. W. Chase, Reveal & M. F. Fay
A basally connate and adnate to C; seeds rounded, surface rugose; embryo long; n = 15, 17; cotyledon?
1/5. Western South America (map: see above, green, from Guaglianone & Arroyo-Leuenberger 2002).
[Ornithogaleae + Urgineeae + Hyacintheae]: rhexigenetic lacunae +; also styloids +; (pollen mixed with raphides).
3B. Ornithogaleae Rouy
Cardenolides +; (A 3; filaments flat, with appendages); seeds flattened/angled; protein crystals in nucleus; n = 2-10+; cotyledon photosynthetic or not.
4/312: Ornithogalum (160), Albuca (110-140). Europe, W. Asia, Africa.
Synonymy: Ornithogalaceae Salisbury
3C. Urgineeae Rouy
Bufadienolides +; bracts spurred [as small leaves in Bowiea]; (stylar canals 3 - Boweia); seeds flattened/winged; testa brittle, not tightly adherent to endosperm; n = 6, 7, 10+ [x = 10]; nucleus without protein crystals.
2(-3?)/105: Drimia (100, inc. Urginea). Mainly Africa, Madagascar, the Mediterranean to India (map: from Pfosser & Speta 2001). [Photos - Boweia Collection.]
Synonymy: Hyacinthaceae Borkhausen
3D. Hyacintheae Dumortier
Homoisoflavanones +; (leaves with pustules or coloured spots); embryo sac variable, e.g. bisporic [micropylar dyad], 8 nucleate [Endymion-type]; seeds (brown to yellow), usu. rounded; elaiosomes common; x = 10.
Age. Crown Hyacintheae are ca 18.8 m.y.o. (Ali et al. 2012).
a. Pseudoprosperineae J. C. Manning & Goldblatt
(Inflorescence branched); bracteole +, ± lateral; 2 ovules/carpel; 1 seed/loculus; n = 9; cotyledon not photosynthetic.
1/1: Pseudoprospero firmifolium. Southeast South Africa (Map: below, blue-green).
[Massoniinae + Hyacinthinae]: ?
Age. The age for this node is ca 17.9 m.y. (Ali et al. 2012).
b. Massoniinae Bentham & Hooker f.
(Bracteole +); (flowers monosymmetric); ovary and style sulcate, style with 3 canals; ovules 2-many/carpel; (elaiosomes +); n = 5-10+, many 20 [x = 10]; cotyledon not photosynthetic (photosynthetic).
Ca 10/260: Lachenalia (135), Ledebouria (70). Africa S. of the Sahara, Ledebouria to India (map: from Venter 2008, red, but inc. blue-green area).
Age. Crown Massoniinae are ca 16.3 m.y.o. (Ali et al. 2012).
Synonymy: Eucomidaceae Salisbury, Lachenaliaceae Salisbury
c. Hyacinthinae Parlatore
(Bracts 0), prophylls quite common; stylar canal papillate; ovules 2-8(-many)/carpel, outer integument 4-5 cells across, parietal tissue 2-3 cells across; antipodal cells large; (elaiosomes +); n = 4-8+ [x = 9]; cotyledon photosynthetic or not.
21/265: Muscari (50), Bellevalia (50), Scilla (30), Prospero (25). Europe (not the northeast), the Mediterranean, the Mid East, North Africa, Barnardia japonica in the Far East (map: Meusel et al. 1965). [Photo: Scilla Collection.]
Age. Crown Hyacinthinae are ca 15.3 m.y.o. (Ali et al. 2012).
Synonymy: Hyacinthaceae Borkhausen, Scillaceae Vest
Evolution. Divergence & Distribution. Divergence in the rest began only ca 18.8 m.y.a. early in the Miocene. The subfamily may have originated in sub-Saharan Africa and dispersed north and also east, but details depend on the analytic method used (Ali et al. 2012). There are about 300 species of Scilloideae in the Cape flora alone (Procheŝ et al. 2006).
Ecology & Physiology. Several species in the foggy deserts of Namaqualand have water-catching leaves with very distinctive morphologies (Vogel & Müller-Doblies 2011).
Pollination Biology & Seed Dispersal. Lachenalia has monosymmetric flowers in which the median member of the outer whorl is in the adaxial position. The same is true of the remarkable monosymmetric flowers of Massonia (Daubneya) aurea that are on the outside of the inflorescence. These flowers have the three abaxial tepals greatly enlarged, while the inner flowers are polysymmetric, the tepals forming a simple, lobed tube; the result is an inflorescence looking like a flower. Pollination in Albuca is noteworthy in that the pollen is deposited by leaf-cutter bees on the tips of the inner tepals, pollination not being completed until two to three days later when the flower withers, the tepals press against the stigma, and the pollen finally germinates (Johnson et al. 2009b, 2012).
Species with myrmecochorous seeds are scattered throughout the subfamily (Lengyel et al. 2010).
Chemistry, Morphology, etc. Some species of Scilloideae have terete, unifacial leaves, and even the bulb scales of some species of Rhadamanthus (= Drimia) are terete. Similar terete leaves are found in Ornithogalum, where they develop from the upper part of the leaf (Kaplan 1973). Urgineeae have a backwardly-directed process at the base of the leaves and/or bracts (c.f. Asparagus: Asparagoideae). Vegetative variation - in both leaf and bulb - is also considerable in Ledebouria (Venter 2007). However, there is less anatomical variation; although mucilage cells are particlarly common in Scilloideae, they also seem to occur elsewhere (Lynch et al. 2006).
Taxa that have tepals with single vascular traces are common in Scilloideae. Some Scilloideae have a filament tube. Wunderlich (1937) described the endosperm as being both helobial and nuclear in Hyacinthineae. Karyotypes may be bi- or even trimodal. The leaves of seedlings are two-ranked.
Information is taken from Speta (1998a: subfamilial classification of Hyacinthaceae, 1998b: general), 2001 (subfamilial characters) and Pfosser and Speta (1999); for chemistry, see Kite et al. (2000), Pfosser and Speta (2001), and Koorbanally et al. (2008), for some embryology, see Eunus (1950) and Berg (1962), for floral morphology in Ledebouriinae, see Lebatha and Buys (2006), and for cytology of some sub-Saharan members, see Goldblatt and Manning (2011) and Goldblatt et al. (2012: base numbers for tribes, etc.).
Phylogeny. The topology [Oziroëeae [Ornithogaleae [Urgineeae + Hyacintheae]]] has moderate support in Manning et al. (2004); Oziroë and Albuca (Ornithogaleae) were successively sisters to the rest at the base of Scilloideae in Seberg et al (2012), the position of the latter genus having only moderate support. There is little well-supported structure along the backbone of Hyacintheae and again within Hyacinthineae in the trnL-F spacer analysis of Wetschnig et al. (2002); the positions of Ornithogaleae and Urgineeae were also unclear. See also Pfosser et al. (2003, 2012), the latter dealing with relationships of the Malagasy taxa.
Classification. For a classification, see Speta (1998a: as Hyacinthaceae). There is considerable disagreement over generic limits here; are there 15 or 45 genera in sub-Saharan Africa? (e.g. Stedje 2001a, b; Pfosser & Speta 2001; Lebatha et al. 2006). See Speta (1998a) for the dismemberment of Scilla and Martínez-Azorín et al. (2011) for that of Ornithogaleae - 19 genera, of which 11 replace Ornithogalum; recognizability of taxa is not the issue. Manning et al. (2004) provide a generic synopsis of the family in sub-Saharan Africa that integrates some morphology with relationships; like them, I take a generally broad view of genera. However, there are unresolved issues that include sampling, whether or not floral syndromes distort ideas of relationships (and so what effect characters taken from these syndromes have in combined analyses), the consequences of maintaining well-known generic names like Albuca and Galtonia as knowlege of phylogeny becomes clearer, and the role cytological data should play. Albuca is recognized in the recent reclassification of Ornithogaloideae by Manning et al. (2009).
Previous Relationships. Chlorogaloideae, until recently included in Hyacinthaceae/Scilloideae (e.g. Pfosser & Speta 1999), are here included in Agavoideae.
[Lomandroideae [Asparagoideae + Nolinoideae]]: steroidal saponins +; pedicels articulated; fruit a capsule; endosperm helobial, thick-walled, pitted, hemicellulosic.
Age. For the age of this node, estimated at (59-)49, 45(-35) m.y., see Bell et al. (2010).
5. Lomandroideae Thorne & Reveal Back to Asparagales
(Naphthoquinones +); (stem secondary growth +); (vessel elements in leaves); (inner T fimbriate; T connate basally); (A adnate to tube); infra-locular septal nectaries +; nucellar epidermal and other cells enlarged; antipodals cells large, inc. nuclei; T persistent in fruit; seeds rounded to angular; cotyledon photosynthetic or not, (coleoptile +; first leaves reduced).
14-15[list]/178. Madagascar, India, South East Asia to the Pacific, and South America, predominantly Australian (Map: the first two groups, Fl. Austr., Schlittler 1951).
5A. Lomandra group
Tubers 0; leaf blade with sclerenchymatous ribs extending from the inner sheath of the vascular bundle to the surface, outer bundle sheath with enlarged cells; leaves two-ranked, flat or curved, (margins prickly), (base auriculate); pedicel articulated (not - Xerolirion); inflorescence units cymose [?all]; flowers long-lived; (pollen grains with encircling sulcus); stigma wet; ovules 1-2/carpel, nucellar cap +, nucellus with central conducting passage; testa thin, tegmen brown, collapsed, cellular, phytomelan 0; endosperm hemicellulosic; n = 7-9, chromosomes 2-7 µm long.
5/65: Lomandra (50). Australia, New Guinea, New Caledonia. [Photo - Inflorescence © K. Stüber.]
Synonymy: Lomandraceae Lotsy
5B. Laxmannia group
Plant with (ecto)/vesicular-arbuscular mycorrhizae; storage roots +; mucilage +; leaves spiral, vernation supervolute or conduplicate, (petiolate), (ligulate); flowers single or in groups, long-lived, pedicel articulated or not; (anthers dehiscing by pores); stigma wet; nucellus with axial conducting tissue; (seed arillate), testa with phytomelan, exotesta often papillate, rest of testa cellular, tegmen thin; endosperm thin-walled; n = 4, 11, chromosomes 0.5-2 µm long.
8/92: Thysanotus (50), Arthropodium (20). South East Asia to Australia, New Zealand and the Pacific.
Synonymy: Eustrephaceae Chupov, Laxmanniaceae Bubani
5C. Cordyline group
Rosette herbs to trees; storage roots +; mucilage +; stomata paracytic, subsidiary cells with oblique divisions; leaves spiral, vernation supervolute or conduplicate, (pseudopetiolate); flowers single, pedicel not articulated; testa with phytomelan, anatomy?; endosperm ?; n = 3, 6, 19 (stamens dimorphic), chromosomes 0.5-2.4 µm long.
2/17. India to the Pacific and New Zealand, tropical America. [Photo - Habit, Flower.]
Chemistry, Morphology, etc. There are reports of cell wall ferulates from Xerolirion (Rudall & Caddick 1994), which is about the only non-commelinid genus with them. In Thysanotus roots, fungi are associated with the subepidermal layer of cells (McGee 1988).
Eustrephus has vessels in its leaves. The leaf of Lomandra and its relatives has sclerenchymatous ribs extending from the inner sheath of the vascular bundles (c.f. also Cordyline?), in Dasypogonaceae this sheath is absent, in Xanthorrhoea it comes from the mesophyll, although the leaves of all three are xeromorphic and superficially similar (Rudall & Chase 1996).
Xerolirion has solitary, terminal carpellate flowers, while its staminate flowers are in cymes. The pollen of Lomandra is very variable, sometimes being spiraperturate (c.f. Aphyllanthes). There is considerable variation in seedling morphology, even within individual groups (Conran 1998).
Additional information is taken from Schlittler (1951: Eustrephus), Chanda and Ghosh (1976: pollen, as Xanthorrhoeaceae), Chase et al. (1996), Conran (1998, as Lomandraceae), and Rudall (1994b, 2000: ovule, etc.).
Classification. I have tentatively recognised three groups above, partly based on morphology, and partly based on molecular data (the Cordyline group - see Chase et al. 1996).
[Asparagoideae + Nolinoideae]: (velamen +); flowers rather small[!]; (fruit a berry); x = 10.
Age. The age of this node is estimated at (55-)44, 42(-34) m.y. by Bell et al. (2010).
Chemistry, Morphology, etc. For ovule development, see Rudall (1994b).
Baccate fruits containing seeds that lack phytomelan are common here, but I do not know where they might be apomorphic. Since the capsular Hemiphylacus and [Comosperma + Eriospermum] are respectively sister to other Asparagaceae and Ruscaceae, baccate fruits are probably derived several times (c.f. Judd et al. 2007).
6. Asparagoideae Burmeister Back to Asparagales
Rhizome +, horizontal or vertical; flavonols, saponins +; vessel elements in roots often with simple perforation plates, vessels also in stem; cuticular wax rodlets parallel; leaves spiral, (scarious - Asparagus), leaf base not sheathing, (cladodes +, flattened or terete - Asparagus); (plant mon- or dioecious); inflorescence ± fasciculate or paniculate; T tube at most short; A basally adnate to T, (3, opposite inner T, outer A staminodial); (G opposite inner T - Hemiphylacus), stigma wet or dry; ovules 2-several/carpel, outer integument ca 6 cells across, nucellar epidermal cells enlarged; embryo sac curved; (fruit a capsule - Hemiphylacus); seed rounded to ± angled; testa multiplicative, collapsing, exotesta massive, tegmen inconspicuous; endosperm cells thick-walled, pitted, embryo long; n = also 56 [Hemiphylacus], chromosomes 1-3 µm long.
2[list]/165-295: Asparagus (160-290!). Old World, but hardly in the Antipodes, also Mexico (map: from Hernandez S. 1995; Hultén & Fries 1986; FloraBase 2007; Seberg 2007; Kubota et al. 2011; B. Ford pers. comm. 2011; Trop. Afr. Fl. Pl. Ecol. Distr. 7. 2012: ?Malesia). [Photo - Flower, Fruit.]
Evolution. Divergence & Distribution. Fukuda et al. (2005a) discuss diversification in Asparagus; this seems to have been rapid and to have started in southern Africa. Hybridization between species seems common in the dioecious subgenus Asparagus (Kubota et al. 2011). Species of Asparagus with flattened cladodes have perfect flowers (Kubota et al. 2011). Asparagus is quite often found in drier/sandy habitats.
Vegetative Variation. There has been much discussion as to what the more or less leaf-like structures in the axils of the leaves in Asparagus "are" - stem or leaf or something else? (see e.g. Arber 1924b - prophyllar, axial; Cooney-Sovetts & Sattler 1986 - homeotic). Nakayama et al. (2012, see also Nakayama et al. 2010) looked at the development of both leaf-like and terete cladodes in Asparagus. The former (A. asparagoides) had an inverted (= prophyllar) orientation, while the latter (A. officinalis) were ventralised (c.f. Allium). They noted that both "leaf" and "stem" genes were expressed in the cladodes; the gene regulatory network for leaf development had been coopted by the axillary shoot (Nakayama et al. 2013).
Chemistry, Morphology, etc. Methyl mercaptans are known from Asparagus.
The prophylls ("bracts") at the bases of the pedicels in Hemiphylacus are described as being lateral (Hernandez S. 1995). For floral development in Asparagus, see Park et al. 2(003, 2004); b-class genes are not expressed in the outer tepal whorl.
Some information is taken from Robbins and Borthwick (1925: ovule and seed), Kubitzki and Rudall (1998: general) and Rudall et al. (1998b).
Phylogeny. For phylogenetic relationships in Asparagus, see Fukuda et al. (2005b) and Kubota et al. (2011); subgenus Myrsiphyllum, at least, is probably paraphyletic. The placement of Eriospermum (Nolinoideae here) as sister to Asparagoideae has quite strong support (Seberg et el. 2012); this position must be confirmed.
Previous Relationships. Hemiphylacus used to be placed in Asphodelaceae (Xanthorrhoeaceae-Asphodeloideae).
Synonymy: Hemiphylacaceae Doweld
7. Nolinoideae Burnett Back to Asparagales
Flavonols, (azetidine-2-carboxylic acid [non-protein amino acid]), (indolizidine alkaloids), (cardenolides), saponins +; (stem secondary growth +); (velamen +); (vessel elements in roots with simple perforation plates; vessels in stem - many ruscoids); (vascular bundles amphivasal); also styloids +; cuticular wax rodlets parallel; leaves (scarious), spiral or two-ranked (opposite - Polygonatum oppositifolium), (petiolate; broad, venation reticulate), margins spiny or not, (leaf base not sheathing); (inflorescence also cymose); (flowers 2-merous - some Maianthemum; T not connate, (to 13, corona + [Aspidistra]; with a single trace); (A adnate to base of tube; connate); pollen often inaperturate/diffuse sulcate; stigma (much expanded), wet; ovules 1-6(-many)/carpel, (micropyle bi-, endostomal), outer integument 2-8 cells across, parietal tissue 1-3(-4) cells across, (0, but lateral tissue), nucellar cap 0 (+), obturator [funicle or ovary wall] +/0, (chalazal vascular bundle branched), raphides +/0; (embryo sac bisporic, 8 nucleate [Allium type]; tetrasporic, 16-nucleate [Drusa type]), (antipodal cells numerous, persistent), (embryo sac haustorium - Dasylirion); (fruit ± a drupe); seeds rounded (angled), (sarcotesta - Ophiopogoneae; testa 0 - Dracaena), phytomelan 0, (phlobaphene +); (endosperm nuclear); n = 5-7, 9, 18-21, chromosomes 0.5-19 µm long (bimodal); cotyledon not photosynthetic, (coleoptile +), primary root well developed, branched or not.
26[list]/475: Dracaena (100), Eriospermum (100), Aspidistra (90), Polygonatum (60), Ophiopogon (55). N. hemisphere, esp. Southeast Asia-Malesia (Convallariaceae s. str.), Europe and the Near East (Ruscaceae s. str.), S.W. North America (Nolinaceae s. str.), Africa, esp. the Cape and S.W. (Eriospermaceae s. str.) (map: from Meusel et al. 1965; Hultén & Fries 1986; Perry 1994, incomplete). [Photo - Ruscus Flower, Eriospermum Flower © M. Elvin.]
Evolution. Pollination Biology & Seed Dispersal. The flowers of Aspidistra, sometimes borne beneath the litter, may have a short corona at the apex of the perianth tube. They often have a large, fungiform stigma, the anthers being hidden below it (Endress 1995b: floral morphology), or the anthers converge towards the centre of the flower; in both cases easy access to the nectar apparently blocked. It has been suggested that such flowers are pollinated by amphipods (Conran & Bradbury 2007 and references) and/or fungus gnats; they look rather like flowers of Asarum and some Burmanniaceae. Other species have more conventional sub-rotate flowers with the stamens and stigma/style grouped in the centre. There may be a dozen or more tepal lobes (see also Hou et al. (2009); Li 2004).
Vegetative Variation. Vegetative variation is particularly impressive. Dracaeana is the only monocot known with a monocot cambium in its roots (Carlquist 2012a). Nolina (ex Nolinaceae) has secondary growth in the stem and is tree-like, while the initiation of the vascular system in the rhizome of Ophiopogon is similar to that in palm stems (Pizzolato 2009).
The leaf blades of some species of Eriospermum have the most remarkable enations on the upper surface. These include fungiform protrusions on the small, crisped, ovate and fleshy blade (E. titanopsoides), a much-branched structure to 12 x 7.5 cm on a much smaller blade (E. ramosum), a bundle of enations with stellate hairs (E dregei), and paired enations that look as if they should grace the helmets of the Valkyries (E. alcicorne: see Perry 1994 for more details). These may be adaptations for catching water from fog (Vogel & Müller-Doblies 2011). The fleshy leaf of Sansevieria (= Dracaena) is developed from the leaf base, the apical portion of the leaf being represented by a Vorlaüferspitze (e.g. Kaplan 1997, vol. 2: chap. 16); depending on the species, the leaf can be developed predominantly from the base (and is flattened) or from the apex (and is terete: Kaplan 1973). Many other taxa, including Maianthemum, have more or less broadly elliptic leaf blades.
Ruscus and its immediate relatives have cladodes, the flowers being born in the middle of a tough, more or less elliptical leaf-like structure. The prophylls are lateral or in some interpretations completely adnate to the axillary shoot, together they form an expanded cladode (Arber 1924a, 1930), or they are homeotic structures (Cooney-Sovetts & Sattler 1987). In any event, the leaves proper are small and scarious and subtend the cladode-like structures (c.f. Asparagus above).
Chemistry, Morphology, etc. Convallarieae are monopodial. Dracaena and relatives have resin canals.
Peliosanthes teta, the only species in Peliosanthes, has an ovary that varies from superior to inferior (Jessop 1976: some recognise more species in the genus). The absence of septal nectaries in some Nolinoideae may be connected with the presence of prominent ovary wall obturators; the latter are possibly derived from the former. In Liriope, etc. (Ophiopogoneae), the seeds, with their fleshy testa (see above), are exposed early in development, so they are semi-gymnospermous.
Additional information can be found in Stenar (1934, 1953) and Wunderlich (1950), all embryology, Björnstad (1970), Lu (1985), Tillich (1995: seed, etc.), Bos (1998: Dracaenaceae), Conran and Tamura (1998: Convallariaceae), Bogler (1998: Nolinaceae), Terry and Rudall (1998: Eriospermaceae), Yeo (1998: Ruscaceae s. str.), Rudall & Campbell (1999: floral morphology), Judd et al. (2002: general), Judd (2003: Ruscaceae S.E. U.S.A.) and Yamashita and Tamura (2004: chromosome evolution in Convallarieae).
Phylogeny The placement of Eriospermum (for which, see Perry 1994) as sister to Asparagoideae has quite strong support (Seberg et el. 2012); it and and the very distinct Comospermum are likely to be sister to the rest of the family; both have capsules and hairy seeds. Note, however, that the hairs on the seeds of the two genera develop in different ways, and Comospermum has two tenuinucellate apotropous ovules/carpel, n = 20 vs. n = 7, etc.; the two genera would at first sight seem to be unrelated (Rudall 1999). The poorly understood Peliosanthes may also be in turn sister to the rest of the family (molecular data alone, e.g. Jang & Pfosser 2002). However, none of these genera was even sub-basal in the study of Seberg et al. (2012), Eriospermum even linking up with Asparagoideae.
Relationships within other Nolinoideae are poorly resolved, although major clades seem to correspond largely with tribes (see Conran & Tamura 1998). However, Convallarieae may be paraphyletic with Aspidistreae and Ruscus and relatives embedded (Yamashita & Tamura 2000: Eriospermum not included; Rudall et al. 2000b); in Ruscus and immediate relatives a mitochondral cox2 intron is missing (Kudla et al. 2002). For relationships of ex-Nolinaceae, -Dracaenaceae, etc., see also Bogler and Simpson (1996).
Classification. There has been debate over the generic limits of Maianthemum, however, a broad circumscription seems appropriate; there is little support for infrageneric groupings within the clade that also includes Smilacina and the combined clade itself is well supported as being monophyletic (Kim & Lee 2007; Meng et al. 2008). Dracaena is to include Pleomele and Sanseviera (e.g. Lu & Morden 2010).
Synonymy: Aspidistraceae Hasskarl, Convallariaceae Horaninow, Dracaenaceae Salisbury, Eriospermaceae d'Orbigny, Nolinaceae Nakai, Ophiopogonaceae Meissner, Peliosanthaceae Salisbury, Polygonataceae Salisbury, Ruscaceae M. Roemer, nom. cons., Sansevieraceae Nakai, Tupistraceae Schnizlein