LIGNOPHYTA

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 controlled by abscisic acid; 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.

MAGNOLIOPHYTA

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; 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 columellar, 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; 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]]]]]: vessels +, elements with elongated scalariform perforation plates; 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]]]]: essential oils in specialized cells [lamina and P ± pellucid-punctate]; tension wood 0; 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]]: (veins in lamina often 7-17mm/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 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; 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; leaves with broad sheath plus blade [not petiole plus lamina], blade linear, main venation parallel, veins joining successively from the outside at the apex, endings not free, margins entire, (teeth spiny), Vorläuferspitze +, leaf base sheathing, sheath open, colleters [intravaginal squamules] +; prophyll single, adaxial; 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 [3], 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; 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; 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; 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].

[DIOSCOREALES + PANDANALES]: outer integument 2(-3) cells across.

Phylogeny. For discussion on the relationship of Pandanales, see the Petrosaviales page.

PANDANALES Berchtold & J. Presl   Main Tree, Synapomorphies.

Nucellar cap +; endosperm type?, (reserves starch), embryo minute. - 5 families, 36 genera, 1345 species.

Note: Possible apomorphies are now being added throughout the site; they 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 because there is very considerable homoplasy for many characters, with with variation within and between clades. Furthermore, basic information for all too many characters is very incomplete, often 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. Stem group Pandanales are dated to ca 124 m.y.a., crown group Pandanales to ca 114 m.y. (Janssen & Bremer 2004), or the crown group may be as young as ca 50 m.y. (Bremer 2000b); comparable figures in Magallón and Castillo (2009) are ca 134.4 and 119.6 (stem: relaxed and constrained penalized likelihood datings) and ca 101.7 (crown) m.y.

Stevenson et al. (2000) suggest other possible characters for the order and groups of families within it. These include a 6 bp deletion in atpA - absent in Talbotia (Velloziaceae), whether or nor it occurs in Barbaceniopsis is unclear (c.f. Davis et al. 2004) - and a distinctively connate androecium; tenuinucellate ovules may be another synapomorphy, and starchy endosperm is common here.

Chemistry, Morphology, etc. Rudall et al. (2005b) note that floral meristicity, usually not very variable in the monocots, varies considerably in Pandanales; floral construction as a whole is rather labile in this order. Some information on pollen morphology is taken from Grayum (1992); for pollen and tapetum, etc., see Furness and Rudall (2006a).

Phylogeny. This grouping of families is somewhat unexpected. The phylogeny above is taken from Behnke et al. (2000, 2013) and especially Caddick et al. (2002a) and Davis et al. (2004: Fig. 1), although Janssen and Bremer (2003) suggested a somewhat different set of relationships; Triuridaceae were not included in these studies.

Triuridaceae often group with Pandanales in molecular analyses (e.g. Chase et al. 2000a: 18S rDNA; Graham et al. 2005); they vary in their relationships within the order. Rudall and Bateman (2006) found another topology in a morphological analysis, in particular, Triuridaceae were nested within Stemonaceae, but without strong bootstrap support (50³%, hardly the robust placement claimed). Morphological characters that support this position included thick filaments, free carpels, and pollen. Clarification of the position of Triuridaceae is needed to understand morphological evolution in this clade (Garay-Arroyo et al. 2012).

Although Triuridaceae were found to be sister to Zingiberaceae in some analyses by Davis et al. (2004), this is an unlikely position, if morphology means anything! Furthermore, Nartheciaceae have sometimes tended to associate with Pandanales, rather than Dioscoreales (q.v. for further details), the clade in which they are included here.



Includes Cyclanthaceae, Pandanaceae, Stemonaceae, Triuridaceae, Velloziaceae.

Synonymy: Cyclanthales Martius, Roxburghiales Martius, Stemonales Doweld, Triuridales J. D. Hooker, Velloziales Reveal

VELLOZIACEAE J. Agardh, nom. cons.   Back to Pandanales

Velloziaceae

Xeromorphic; vessel elements in roots often with simple perforation plates, vessels also in stem and leaf [?ref.]; phloem in at least smaller bundles in two abaxial-lateral strands; sieve tube plastids in the stem 1³ µm across; cortex in three zones; stomata brachyparacytic; leaves persistent; inflorescences axillary; flowers violet, large; A borne in mouth of "hypanthium", anthers bisporangiate, monothecal; pollen bi- or trinucleate; ovary inferior, placentae bifid, stalked-capitate, style long; ovules many/carpel, parietal tissue absent; fruit dehiscing down sides, loculicidal; endosperm with starch.

5[list]/240. South America and Africa-Madagascar to Arabia, China.

1. Acanthochlamydoideae P. C. Kao

Caespitose rhizomatous herb; steroidal saponins +?; root stele tetrarch, pith absent; lateral roots arise opposite xylem poles; cauline vascular tissue aggregated in the centre of the stem; vessels also in stem and leaf, elements with simple perforation plates; scape with a root-like vascular cylinder; raphides and tannin cells 0; palisade tissue 0; midrib with back-to-back vascular bundles; leaves spiral, ligule basal, surrounding stem; inflorescence scapose, compound capitate, leaf adnate to scape; T ca 1/2 connate; anthers short, filaments short; septal nectaries 0; "seed coat" ca 2 cells across, walls ± lignified, testa cells ± elongated, tegmen tanniniferous; embryo large/medium; n = 19; seedling?

1/1: Acanthochlamys bracteata. S.E. Tibet and S.W. China (Map: from Ying et al. 1993 - green). [Photo - Flower] [Photo - Fruit]

Synonymy: Acanthochlamydaceae P. C. Kao

2. Vellozioideae Rendle

Woody or herbaceous, adventitious roots often growing down through persistent leaf bases; biflavonoids + [Xerophyta]; (velamen +); (vessels not in stem and leaf; vessel elements with scalariform perforation plates); sieve tube plastids with angular crystals and other loosely-packed crystals; transfusion tracheids in leaf bundles; (raphides/styloids +); stomata in grooves, (on both surfaces), (cuticular waxes as aggregated rodlets), leaves with marginal bundles and transfusion tissue; indumentum various; leaves (spirally)3-ranked, vernation conduplicate-flat, midrib +, margins usu. spiny; inflorescences often single-flowered, bracteoles lateral; hypanthium +/0; median T in outer whorl adaxial [e.g. Barbacenia], T largely free; (corona +, usu. adnate to adaxial A); (A not adnate to T), (3 or 6 fasciculate [A in fascicle connate], development within fascicles ± centripetal), filaments cylindrical, anthers long, (dithecal); (pollen in tetrads); septal nectaries +; stigmas large, erect or spreading, capitate; micropyle bi(endo)stomal, endothelium and funicular obturator +, suprachalazal tissue massive; fruit also poricidal or with intercostal apertures; testa ± tanniniferous, exotesta thickened or not, tegmen compressed, tanniniferous; endosperm helobial, cells elongated, wall formation in small chalazal chamber precedes that in large micropylar chamber, embryo medium to short; n = 7, 8, 17, 24 [x = 12?]; collar rhizoids +.

4/240: Vellozia (105), Barbacenia (90). South America and Africa-Madagascar (to Arabia) (Map: see Ayensu 1973b - red). [Photo - Habit, Flower.]

Synonymy: Barbaceniaceae Arnott

Evolution. Divergence & Distribution. Stem group Velloziaceae are dated to ca 108 m.y., crown group Vellozioideae to a mere ca 14 m.y. (Janssen & Bremer 2004: Velloziaceae and Stemonaceae are sister taxa, Acanthochlamys not included). Mello-Silva et al. (2011) interpret the split of Acanthochlamys from the rest of the family in terms of a drift-induced vicariant event.

Ecology & Physiology. Velloziaceae include many dessication-tolerant taxa of inselbergs, and a number of arborescent taxa (Farrant 2000: Xerophyta; Naidoo et al. 2009: Xerophyta viscosa, analysis of substances secreted on adaxial surface of the leaf). The true stem is small, and soon rots away, the "trunk" consisting of roots, each initially with a velamen, and persistent leaf bases (Porembski 2006).

Chemistry, Morphology, etc. The roots of Acanthochlamys are tetrarch or triarch and lack pith, and so are unlike the roots of most other monocots. The anatomy of the stem/rhizome of Acanthostachys is unclear; it seems to consist of perhaps four vascular bundles in the centre, almost touching, and apparently with a small amount of non-vascular tissue in the middle (Kao 2012). The anatomy of the scape has been described as "similar to that of a leaf ensheathing a rhizome" (Kao & Kubitzki 1998: 56), although the central part of the stem is more like a root, not a rhizome. The leaves of Acanthochlamys have a rather large basal adaxial ligule ensheathing the stem; the other genera have sheathing bases. Phloem in the "midrib" bundles of the leaves is sometimes arcuate, but in smaller bundles in particular it is broken up into two abaxial-lateral strands (Smith & Ayensu 1976). Amaral and Mello-Silva (2005, esp. 2008) suggest that the tetracytic stomata of Vellozioideae are better thought of as paracytic.

The single flowers/inflorescences are apparently always axillary (Kubitzki 1998b). What is described here as the hypanthium in Velloziaceae may bear the same indumentum as occurs on the petiole; assuming the traditional interpretation of a hypanthium, the perianth members here would usually be more or less free. Even so, the stamens may be adnate to the tepals for most of their length, as in Barbaceniopsis. The corona develops late, and although partly associated with the bases of the filaments, its vasculature is in part tepalline (Sajo et al. 2010: q.v. also for androecial development). In Acanthochlamys the anthers opposite the inner tepal members are inserted higher up on the tube than the anthers opposite the outer members.

Additional information is taken from Ayensu (1973a: general), Smith and Ayensu (1976: monograph - with anatomy - of New World taxa), de Menezes (1980: androecial evolution), Williams et al. (1991: chemistry), Kubitzki (1998b: general), Kao and Kubitzki (1998: as Acanthochlamydaceae, much detail), Behnke et al. (2000: general;, 2013: anatomy of the blade of Xerophyta), Strassburg and de Menezes (2001: development) and Kao (1989) - Kao and Gao are one and the same.

Phylogeny. Talbotia (African) is mesophytic and its filaments are not adnate to the perianth. It is perhaps sister to the other Vellozioideae (but c.f. Behnke et al. 2000), however, basal relationships are unresolved. Barbacenia is paraphyletic, but Barbacenioideae are monophyletic (corona +; n = 7). Vellozioideae sensu Menezes are paraphyletic (Salatino et al. 2001), however, there is considerable disagreement between the topologies implicit in different morphology-based classifications of the family (Mello-Silva 2005), and that in Mello-Silva is only partly congruent with that of the molecular tree of Behnke et al. (2000, 2013). Nevertheless, Acanthochalmys is clearly sister to the rest of the family (Behnke et al. 2000, 2013; Mello-Silva 2005). In a joint molecular and morphological study, Mello-Silva et al. (2011) found the relationships [Acanthochlamys [Xerophyta (inc. Talbotia) + the rest (support not strong)]] (see also Behnke et al. 2013: support much ihgher in Bayeisan than ML analyses), and suggest a number of apomorphies for the main clades, although optimisation of some of them is difficult. Forb relationships within Xerophyta, see Behnke et al. (2013).

Classification.Although Acanthochalmys, sister to the rest of the family, is morphologically and anatomically distinct, subfamilial status is appropriate (Behnke et al. 2000; Mello-Silva 2005; c.f. Gao 2012); if a family, it would be monotypic, and Velloziaceae s.l. are well characterized. For suggestions as to generic limits in the family, see Mello-Silva et al. (2011).

[Triuridaceae, [Stemonaceae [Pandanaceae + Cyclanthaceae]]: septal nectaries 0.

TRIURIDACEAE Gardner, nom. cons.   Back to Pandanales

Triuridaceae

Plant myco-heterotrophic, echlorophyllous; chemistry?; root hairs 0-many; vessels 0; root stele solid; stem with vascular bundles in a single ring, (endodermis +); crystals 0; plant glabrous; cuticular waxes as parallel series of platelets, within a series transversely arranged; stomata 0; leaves spiral, reduced, (base sheathing; closed); inflorescence racemose, bracteole 0; T valvate, ?trace number, (nectary +); A connate or not, filaments stout; tapetum cells uninuclear; pollen trinucleate, inaperturate, surface gemmate, gemmae with protruberances or spines; G 10-many, plicate, styles solid, no transmitting tissue, stigma penicillate to smooth, ?dry; ovules basal, parietal tissue absent, nucellar cap 0, endothelium, hypostase +; seeds endotestal, cuticle below very thick, exotesta persisting; endosperm hemicellulosic, copious, almost a chalazal haustorium; n = 9, 11, 12(-16); seedling?

11[list]/50. Pantropical (map: from van de Meerendonk 1984; Maas & Rübsamen 1986; Rübsamen-Weustenfeld 1991; Trop. Afr. Fl. Pl. Ecol. Distr. 7. 2012).

1. Sciaphileae Miers

Plant monoecious, (flowers perfect); T 4, 6, 8, (basally connate), apex acute, with a tuft of hairs or not; A 2, 3, 4, 6, anther dehiscence diagonal-transverse (vertical); tapetum plasmodial; pollen (monosulcate - Sciaphila), 24-40 µm across; style gynobasic; ovule 1/carpel; fruit a follicle; seed with testal cells on chalazal side collapsed, or small, thickish walled, over rest of seed endotestal cells large and radially elongated, wall thickenings radial.

5/40: Sciaphila (30). Mostly Old World, esp. Indo Malesia and the Pacific, few New World. [Photo - Sciaphila].

2. Triurideae Miers

Root hairs few to none; plant usually dioecious; T 3, 6, apex caudate, (connate basally); staminate flowers: A 3, 6, anther dehiscence longitudinal, pollen 15-21 µm across; pistillate flowers: carpel development centrifugal [Triuris], style (sub)terminal; ovule 1/carpel; embryo sac tetrasporic, the three chalazal megaspores fuse, divide twice, 7-celled and 8-nucleate, the antipodals triploid [Fritillaria-type]; fruit an achene; endotestal cells with wall thickenings parallel to long axis of seed; endosperm pentaploid, initially with starch.

4/7. American Tropics. [Photo - Triuris.]

3. Kupeaeae Cheek

Root hairs none; inflorescence a spike; plant dioecious; T 4, apex acute; staminate flowers: (bract adnate to flower - Kupea), flower monosymmetric; (T basally connate), with a single trace [Kupea]; A 4, anther dehiscence transverse, pollen ca 25 µm across; pistillate flower: style (sub)terminal; ovules 2/carpel, hemitropous to campytotropous; fruit indehiscent.

2/3. Africa; Cameroon and Tanzania.

Evolution. Divergence & Distribution. Despite the delicate nature of plants of this family, fossil flowers of Triuridaceae (two genera) are known from ca 90 m.y. rocks in New Jersey (Gandolfo et al. 1998a, 2002). They were then the earliest monocot fossils known, but that honour has now been taken by Araceae (see Friis et al. 2004), and anyhow their identification has been questioned (Friis et al. 2011).

Rübsamen-Weustenfeld (1991) lists other characters especially of endosperm and embryo size and seed anatomy that separate Sciaphileae and Triuridae; some may turn out to be apomorphies, but Kupeaeae are poorly known.

Lacandonia schismatica (the genus has recently been found in Brazil) has stamens borne inside the carpels, almost unique in angiosperms. Although it has been suggested that these "flowers" may be pseudanthia (Rudall 2003b), heterotopy is a more likely explanation (Ambrose et al. 2006; esp. Álvarez-Buylla et al. 2010; Garay-Arroyo et al. 2012, interestingly, the carpels still develop after the stamens, despite their reversed positions (Garay-Arroyo et al. 2012).

Pollination Biology. Lacandonia can self pollinate: Pollen grains germinate while still in the anther and the tubes grow through the tissue of the flower to the ovule (Márquez-Guzmán et al. 1989). In general, polllination by small flies is likely (Rudall & Bateman 2006).

Chemistry, Morphology, etc. Mycorrhizae are of the Paris type (Imhoff 1998). The roots lack pith (von Guttenberg 1968) and the root stele is monarch or diarch - the entire stele from the endodermis inwards may be lignified (Johow 1889 and references).

The tiny staminate flowers of Kupea and Kihansia are quite strongly monosymmetric (Cheek 2003a; Rudall et al. 2007b). Endress (1995b) illustrated more or less paired tepal nectaries for Triuris. Staminate and carpellate flowers usually lack rudiments of pistils and stamens respectively. Inter- and intraspecific variation in the number of parts of the flower is considerable (see Rübsamen-Weustenfeld 1991; Maas-van der Kamer 1995; Rudall et al. 2007b). In the perfect flowers of Lacandonia and carpellate flowers of Triuris individual carpel primordia develop on compound primordia, and in the former stamen and carpel primordia develop from a common precursor. Rudall (2008) suggested that the basic construction of the gynoecium in at least some Triuridaceae is fasciculate, the fascicles being radially elongated, but there is considerable variation in gynoecial development (see also Rübsamen-Weustenfeld 1991). Although some Triuridae have tetrasporic embryio sacs of the Fritillaria-type, ordinary monosporic Polygonum-type embryo sacs have also recently been reported here (Espinosa-Matiás et al. 2012). The strong asymmetry of the seeds, apparently restricted to some Sciaphileae (e.g. Wirz 1910, c.f. Batygina et al. 1990: interpretation difficult, plane of sections?), means that they are more or less winged on one side.

Additional information: For ovule and seed, see Johow (1889), for carpels, etc., Igersheim et al. (2001), for pollen, etc., Furness et al. (2002a), and for general information, Rübsamen-Weustenfeld (1991) and Maas-van der Kamer and Weustenfeld (1998).

Phylogeny. In morphological analyses Kupea was sister to the rest of the family and Sciaphileae were paraphyletic (Rudall & Bateman 2006: Kihansia not included). Recognition of Lacandonia as a genus may make Triuris paraphyletic (Vergara-Silva et al. 2003); if this relationship is confirmed, the morphological context for an explanation of the distinctive floral construction of Lacandonia becomes very specific indeed.

Classification. For tribes, I follow Rübsamen-Weustenfeld (1991) and Cheek (2003a); the latter described external morphology only for Kupeaeae.

Previous Relationships. Triuridaceae have often been associated with Alismataceae and relatives, all having separate carpels and so assumed to be primitive.

Synonymy: Lacandoniaceae E. Martínes & Ramos

[Stemonaceae [Pandanaceae + Cyclanthaceae]]: (styloids +); flowers other than 3-merous; placentation parietal, style 0.

STEMONACEAE Caruel, nom. cons.   Back to Pandanales

Stemonaceae

Plant monopodial, (tuberous), with scale leaves, stem erect (twining); (unspecified saponins - Stemona), alkaloids with pyrrolo- or pyrido(1,2,-alpha)- azepine nucleus, +; stem vascular bundles in 1 or 2 rings, those of inner or only ring amphivasal; vessel elements with scalariform perforation plates also in stem; petiole bundles in arc; (styloids +); plant glabrous; leaves two-ranked or opposite, petiolate, not sheathing, midrib simple (not distinct), cross veins fine, well developed, scale leaves +, sheathing; inflorescences axillary, cymose or flowers single; (flower monosymmetric - Croomia heterosepala), pedicel articulated; T 4(-5), perianth tube short; A adnate to base of T, ± connate, (apex of anther sterile), connective expanded, (apiculate); pollen spiny, gemmate; G 1 to [3], (inferior), placentae apical or basal, style branches ± separate; ovules 2 to many/carpel, outer integument to 5 cells across, inner integument to 3 cells across, parietal tissue (0?-2) cells across; fruit a capsule [?type]; seeds longitudinally ridged, aril of uniseriate or vesicular hairs from hilum, raphe or micropyle; testa multiplicative, several-layered, ridges many cells high, tanniniferous, inner 4 layers thick-walled, (test ca 2 layers across, radial wall of exotesta thickened, forming the ridge - Pentastemona), (tegmen persists, cell walls thickened); endosperm copious, starchy, walls not pitted; n = 7, 9, 12; seedling with non-photosynthetic cotyledon, primary root well developed.

4[list]/27. China and Japan to Australia, S.E. U. S. A. (Croomia ) (map: from Duyfjes 1993; Fl. N. Am. 26: 2002). [Photo - Croomia - Habit.].

Evolution. Divergence & Distribution. Stem group Stemonaceae are dated to ca 108 m.y., the crown group to ca 84 m.y. (Janssen & Bremer 2004).

Pollination Biology & Seed Dispersal. At least some Stemonaceae are pollen flowers (Vogel 1981).

Myrmecochory is common in seeds of the family (Lengyel et al. 2010).

Chemistry, Morphology, etc. The distinctive alkaloids found in Stemonaceae with their pyrrolo- or pyrido(1,2,-alpha)-azepine nucleus (see also Pilli & Ferreira de Oliveira 2000) are probably an apomorphy of the family. Duyfjes (1992) inadvertently suggested that Stemonaceae s. str. - i.e. not including Pentastemona - lacked scale leaves, however, these are well documented on the underground parts (e.g. Tomlinson & Ayensu 1968), while van Steenis (1982) noted that they were sheathing and compared this feature to the sheathing photosynthetic leaves of Pentastemona, suggesting an equivalence. Stemona, etc., do not have sheathing leaves.

The morphology of the inflorescence and the nature of the breeding system of Pentastemona need more study - also its anatomy, chemistry, etc. Stemona phyllantha has epiphyllous inflorescences. The anatomy of the seed ridges varies considerably.

Additional information is taken from Duyfjes (1991) and Kubitzki (1998b), both general, Swamy (1964b) and Bouman and Devente (1992), both ovules and seeds, , Endress (1995b: flowers of Pentastemona), Furness and Rudall (2000b: pollen aperture number) and Rudall et al. (2005b: floral morphology).

Phylogeny. Pentastemona appears to be well embedded within the family (e.g. Jiang et al. 2006: molecular data, c.f. Rudall & Bateman 2006: morphological analysis); on balance, its distinctive features are likely to be derived.

Synonymy: Croomiaceae Nakai, Pentastemonaceae Duyfjes, Roxburghiaceae Wallich

[Pandanaceae + Cyclanthaceae]: stem vascular bundles compound; styloids +; stomata tetracytic, subsidiary cells with oblique cell divisions; leaves ± plicate-appearing when mature; inflorescence bracts conspicuous, inflorescence a dense spike or head [a spadix], inflorescence bracts coloured or not; flowers sessile; flowers imperfect; staminate flowers: stamens usu. several-many; pollen porate; pistillode +; carpellate flowers: staminodes +; ovules apotropous, with radiating subepidermal nucellar/chalazal cells, many/carpel; fruit an indehiscent syncarp [baccate or drupaceous]; endotesta well developed, internally to that are two persistent cuticular layers; cotyledon not photosynthetic, seedling with all internodes ± elongated.

Evolution. Divergence & Distribution. The divergence between the two families has been dated to ca 98 m.y. (Janssen & Bremer 2004).

Chemistry, Morphology, etc. The compound vascular bundles can sometimes be seen under a hand lens; the vascular bundles have groups of vessels at opposite ends with smaller cells in between. There are vessels in the leaves in Pandanaceae, but not in Cyclanthaceae (see Carlquist 2012a for xylem anatomy).

Phylogeny. A close relationship between this pair of families in consistently obtained in molecular studies and also has strong morphological support.

Previous relationships. A group recognised in the past was the Spadiciflorae; this included those taxa with a spadix and often also a spathe, i.e. Pandanaceae, Cyclanthaceae, Araceae and Arecaceae. These families are now placed in three orders, Pandanales, Alismatales and Arecales. Engler (1892) linked Pandanaceae, Arecaceae and Cyclanthaceae.

PANDANACEAE R. Brown, nom. cons.   Back to Pandanales

Pandanaceae

Plant woody, habit various, trees, shrubs, or climbers with roots from leaf axils, rhizomes 0; vessels elements also in stem and leaf, perforation plates scalariform; sieve tube plastids also with peripheral fibres; (cuticular waxes as aggregated rodlets); leaves spirally three- or four-ranked, vernation conduplicate-flat, M-shaped when mature, spiny, (sheaths closed; base auriculate - Freycinetia); plant dioecious (monoecious); (inflorescence branched, paniculate, flowers single - Sararanga); (pedicel + - Sararanga sinuosa]; P connate as cupule [Sararanga] to 0; staminate flowers: A 1-many, variously free to connate or aggregated [on underside of peltate structure]; pistillode 0; pollen exine three-layered [level?]; pistillode + (0); carpellate flowers: staminodes + (0); G 1-several, free to connate, intra-ovarian trichomes +; ovule 1/carpel (many - Freycinetia), apotropous, (micropyle bistomal), parietal tissue 1-5 cells across, (nucellar cap ca 2 cells across), obturator and hypostase +; embryo sac incorporating nucellar cells at chalazal end, (bisporic - Pandanus); fruit baccate or drupaceous; seed coat thin, (testa ca 5 layers thick, exotesta developed - Sararanga); (endosperm starchy); n = 25, 28, 30; hypocotyl long [Freycinetia], primary root branched [Pandanus].

4[list]/885: Pandanus (650), Freycinetia (180), Benstonea (50). W. Africa to the Pacific (map: see Heywood (1978: Africa); Callmander et al. 2003). [Photos - Staminate Flower, Carpellate Flower.]

Evolution. Divergence & Distribution. Crown group Pandanaceae began to diverge ca 51 m.y.a. (Janssen & Bremer 2004), however, Callmander et al. (2003) discuss the biogeography of the famaly in the context of the Gondwanan break-up. The pollen genus Pandaniidites is known from North America where it spans the Cretaceous-Tertiary boundary and has been found in rocks up to 70 m.y. old (Hotton et al. 1994). However, it has since been shown that Pandaniidites is associated with flowers of Limnobiophyllum, to be assigned to Araceae-Lemnoideae (Stockey et al. 1997; Stockey 2006).

Pollination Biology & Seed Dispersal. The development of staminate and carpellate flowers seems to be quite labile in Freycinetia, and sex changes of plants have been recorded (Huynh 1992 and literature).

Chemistry, Morphology, etc. Since there is no perianth, the position of the ovary is often difficult to ascertain, but it is clearly superior in some species of Freycinetia (e.g. Huynh 1991, 1992) at least. The carpels vary from free to variously connate and fasciate, and their orientation varies from centripetal to centrifugal (c.f. Cercidiphyllum!), sometimes within a single floral unit (Stone 1968). The embryo sac of Pandanus appears to have extra antipodal cells, however, these come from the nucellus (see Maheshwari 1955 for discussion).

Some information, including testa anatomy, is taken from Fagerlind (1940a: Pandanus seems not always to have a bisporic embryo sac), Strömberg (1956), and Cheah and Stone (1975), all embryology, Zimmermann et al. (1974: vascular organization in the stem), Dahlgren et al. (1985: general), Hotton et al. (1994: pollen), Stone et al. (1998; general), and Huynh (2001: Sararanga).

Phylogeny. For early studies of the phylogeny of the family, see Stevenson and Loconte (1995: and Cox et al. (1995). Callmander et al. (2003) did not show the full tree they obtained, albeit it was apparently poorly resolved. In a tree with more limited taxonomic but greater gene sampling, relationships were [Pandanus [Martellidendron, Freycinetia, Sararanga]] (Callmander et al. 2003). Buerki et al. (2012b: sampling extensive) found the well-supported set of relationships [Saranga [Freycinetia [Acrostigma clade, core Pandanus, Martellidendron]], while Nadaf and Zanan (2012: Indian species the focus) recovered the relationships [[Benstonea + Pandanus] [Sararanga [Freycinetia + Martellidendron]]].

Classification. Callmander et al. (2003, 2012) have been dividing the large genus Pandanus; the segregates can be identified only with fertile material, sometimes pistillate alone...

Botanical Trivia. Gill and Tomlinson (1975) note that the apices of aerial roots of Pandanus may be up to 11 cm in diameter.

Synonymy: Freycinetiaceae Le Maout & Decaisne

CYCLANTHACEAE A. Richard, nom. cons.   Back to Pandanales

Cyclanthaceae

Large herbs; vascular tracheids or vessels in root and leaf; petiole bundles scattered; (mucilage cells +); leaves spirally two-ranked, petiolate, often divided deeply, vernation plicate or variants; plant monoecious; inflorescence (branched), spadiciform; staminate flowers: pollen lacking endexine lamellae; carpellate flowers: ovules (epitropous), micropyle bistomal, outer integument 3-5 cells across, nucellar cap 2-3 cells across, parietal tissue absent, (hypostase +), (postament +); endosperm helobial, embryo short; collar rhizoids +.

12/225: Central and tropical South America (map: from Harling 1958; fossil Cyclanthus [blue] from Smith et al. 2009).[List]

Cyclanthoideae

Subepidermal sclereids +; non-articulated laticifers +; lysigenous air spaces with transverse septae +; lamina vernation modified plicate, blade 2-costate; inflorescence with whorls of staminate and carpellate "flowers"; P 0; staminate flowers: A in 4 rows per whorl, connate basally; carpellate flowers: G with ovary cavity with closely-set placentae; ovules lacking nucellar cap, funicles long; fruit dry, syncarpous, carpellary annulus sliding off the inflorescence axis and splitting down the middle; seeds ridged, embedded in mucilage; endotestal cells palisade, inner periclinal walls granular; n = 9.

1/1: Cyclanthus bipartitus. Central and N. South America, the Lesser Antilles. [Photo - Flower.]

Carludovicioideae

Many epiphytes and climbers; cork subepidermal or outer cortical; (styloids +); leaves (two-ranked), 1- or 3-costate, (hastula +); inflorescences (axillary), flowers in spirals; staminate flowers: P in one (two) whorls, 6+ (-30), with abaxial gland (none); A ca 10-many, filaments swollen basally; carpellate flowers: 4(-8)-merous; staminodes long-filiform, opposite P; G 4, ± inferior, alternating with P, (placentae apical); ovules many/carpel; fruit baccate, syncarpous or not, apically circumscissile or with other unusual methods of opening; (seeds exotegmic); (endosperm starchy); n = 9, 15, 16.

11/225: Asplundia (100), Dicranopygium (50), Sphaeradenia (50). Central and tropical South America, the Greater Antilles. [Photo - Flower, Fruit.]

Evolution. Divergence & Distribution. Crown group Cyclanthaceae may begin to diverge ca 77 m.y.a. (Janssen & Bremer 2004). Interestingly, Cyclanthus has quite recently been identified from the European Eocene (seeds had previously been misidentified as a Scirpus), where it may even be a diagnostic element of the vegetation - along with Nypa (Smith et al. 2008; see also Collinson et al. 2012). This changes how one thinks of the evolution and distribution of the family.

Pollination Biology & Seed Dispersal. Carludovicia is associated with derelomine flower weevils the adults of which pollinate the flowers while the larvae eat the developing seeds (Franz 2004). Indeed, weevils in general are commonly associated with cyclanthaceous inflorescences, and their larvae may eat the gynoecia (Harling 1958).

The fruits of Carludovicioideae are baccate, syncarpous or not, and are apically circumscissile or have other unusual methods of opening. For example, the subfleshy infructescences of genera like Carludovica open irregularly from the apex as the outer part of the infructescence (the apical parts of the connate gynoecia) recurves and pulls away, exposing the brightly-coloured interior. Dispersal is by animals.

Chemistry, Morphology, etc. For leaf morphology and development, the latter rather like that in broad leaved angiosperms, see Wilder (1976). Further information on the morphology and vernation of leaves is given by Wilder (1981a, b) and on growth habit by Wilder (1992).

In staminate flowers, both perianth and stamen number may increase. There is considerable variation in pollen morphology and seed morphology and anatomy; Furness and Rudall (2006) suggest that the pollen grains of Cyclanthaceae, alone in the order, lack endexine lamellae.

For information on embryology, see Harling (1946), for seeds, see Smith et al. (2008), and for much information on just about everything, see Harling (1958) and Harling et al. (1998).

Phylogeny. For a detailed morphological phylogeny of the family, see Eriksson (1994).