EMBRYOPSIDA Pirani & Prado
Gametophyte dominant, independent, multicellular, thalloid, with single-celled apical meristem, showing gravitropism; rhizoids +, unicellular; acquisition of phenylalanine lysase [PAL], phenylpropanoid metabolism [lignans +, flavonoids + (absorbtion of UV radiation)], xyloglucans +; plant [protoplasm dessication tolerant], ectohydrous [free water outside plant physiologically important]; cuticle +; cell wall also with (1->3),(1->4)-ß-D-MLGs [Mixed-Linkage Glucans]; chloroplasts per cell, lacking pyrenoids; glycolate metabolism in leaf peroxisomes [glyoxysomes]; centrioles in vegetative cells 0, metaphase spindle anastral, predictive preprophase band of microtubules, phragmoplast + [cell wall deposition spreading from around the spindle fibres], plasmodesmata +; antheridia and archegonia jacketed, stalked; spermatogenous cells monoplastidic; blepharoplast, bicentriole pair develops de novo in spermatogenous cell, associated with basal bodies of cilia [= flagellum], multilayered structure [4 layers: L1, L4, tubules; L2, L3, short vertical lamellae] + spline [tubules from L1 encircling spermatid], basal body 200-250 nm long, associated with amorphous electron-dense material, microtubules in basal end lacking symmetry, stellate array of filaments in transition zone extended, axonemal cap 0 [microtubules disorganized at apex of cilium]; male gametes [spermatozoids] with a left-handed coil, cilia 2, lateral; oogamy; sporophyte dependent on gametophyte, embryo initially surrounded by haploid gametophytic tissue, plane of first division horizontal [with respect to long axis of archegonium/embryo sac], suspensor/foot +, cell walls with nacreous thickenings; sporophyte multicellular, with at least transient apical cell [?level], sporangium +, single, dehiscence longitudinal; meiosis sporic, monoplastidic, microtubule organizing centre associated with plastid, cytokinesis simultaneous, preceding nuclear division, sporocytes 4-lobed, with a quadripolar microtubule system; spores in tetrads, sporopollenin in the spore wall laid down in association with trilamellar layers [white-line centred lamellae], white-line centred lamellae increase in numbers; nuclear genome size <1.4 pg, LEAFY and KNOX1 and KNOX2 genes present, ethylene involved in cell elongation; chloroplast genome with close association between trnLUAA and trnFGAA genes.
Many of the bolded characters in the characterization above are apomorphies of subsets of streptophytes along the lineage leading to the embryophytes, not apomorphies of crown-group embryophytes per se.
All groups below are crown groups, nearly all are extant. Characters mentioned are those of the immediate common ancestor of the group,  contains explanatory material, () features common in clade, exact status unclear.
Abscisic acid, ?D-methionine +; sporangium tapetum +, secreting sporopollenin, outer white-line centred lamellae obscured by sporopollenin, columella + [developing from endothecial cells], seta developing from basal meristem [between epibasal and hypobasal cells]; stomata +, anomocytic, cell lineage that produces them with symmetric divisions [perigenous]; underlying similarities in the development of conducting tissue and in rhizoids/root hairs; spores trilete; polar transport of auxins and class 1 KNOX genes expressed in the sporangium alone; shoot meristem patterning gene families expressed; MIKC, MI*K*C* and class 1 and 2 KNOX genes, post-transcriptional editing of chloroplast genes; gain of three group II mitochondrial introns.
[Anthocerophyta + Polysporangiophyta]: archegonia embedded/sunken in the gametophyte; sporophyte long-lived, chlorophyllous; sporophyte-gametophyte junction interdigitate, sporophyte cells showing rhizoid-like behaviour.
Sporophyte branched, branching apical, dichotomous; sporangia several, each opening independently; spore walls not multilamellate [?here].
EXTANT TRACHEOPHYTA / VASCULAR PLANTS
Photosynthetic red light response; plant homoiohydrous [water content of protoplasm relatively stable]; control of leaf hydration passive; (condensed or nonhydrolyzable tannins/proanthocyanidins +); sporophyte soon independent, dominant, with basipetal polar auxin transport; lignins +; vascular tissue +, G- and S-type tracheids, sieve cells + [nucleus degenerating], tracheids +, in both protoxylem and metaxylem, plant endohydrous [physiologically important free water inside plant]; endodermis +; leaves spirally arranged, blades with mean venation density 1.8 mm/mm2 [to 5 mm/mm2]; sporangia adaxial on the sporophyll, derived from periclinal divisions of several epidermal cells, wall multilayered [eusporangium]; columella 0; tapetum glandular; gametophytes exosporic, green, photosynthetic; basal body 350-550 nm long, stellate array in transition region initially joining microtubule triplets; placenta with single layer of transfer cells in both sporophytic and gametophytic generations, root lateral with respect to the longitudinal axis of the embryo [plant homorhizic].[MONILOPHYTA + LIGNOPHYTA]
Sporophyte branching ± indeterminate; root apex multicellular, root cap +, lateral roots +, endogenous; endomycorrhizal associations + [with Glomeromycota]; G-type tracheids +, with scalariform-bordered pits; leaves with apical/marginal growth, venation development basipetal, growth determinate; sporangia borne in pairs and grouped in terminal trusses, dehiscence longitudinal, a single slit; cells polyplastidic, microtubule organizing centres not associated with plastids, diffuse, perinuclear; blepharoplasts +, paired, with electron-dense material, centrioles on periphery, male gametes multiciliate; chloroplast long single copy ca 30kb inversion [from psbM to ycf2]; LITTLE ZIPPER proteins.
Sporophyte woody; lateral root origin from the pericycle; branching lateral, meristems axillary; cork cambium + [producing cork abaxially], vascular cambium bifacial [producing phloem abaxially and xylem adaxially].
Plants heterosporous; megasporangium surrounded by cupule [i.e. = unitegmic ovule, cupule = integument]; pollen lands on ovule; megaspore germination endosporic [female gametophyte initially retained on the plant].
EXTANT SEED PLANTS / SPERMATOPHYTA
Plant 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 particularly with guaiacyl and p-hydroxyphenyl [G + H] units [sinapyl units uncommon, no Maüle reaction]; root stele with xylem and phloem originating on alternate radii, cork cambium deep seated; mitochondrial density in whole SAM 1.6-6.2[mean]/μm2 [interface-specific mitochondrial network]; stem with vascular cylinder around central pith [eustele], phloem abaxial [ectophloic], endodermis 0, xylem endarch [development centrifugal]; 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 +; cork cambium superficial; leaf nodes 1:1, a single trace leaving the vascular sympodium; stomatal pore with active opening in response to leaf hydration, control by abscisic acid, metabolic regulation of water use efficiency, etc.; axillary buds +, exogenous; prophylls two, lateral; leaves with petiole and lamina, development basipetal, blade simple; plant heterosporous, sporangia borne on sporophylls, sporophylls spiral; microsporophylls aggregated in indeterminate cones/strobili; grains monosulcate, aperture in ana- position [distal], primexine + [involved in exine pattern formation with deposition of sporopollenin from tapetum there], exine and intine homogeneous; megasporangium indehiscent; ovules with parietal tissue 2+ cells across, megaspore tetrad linear, functional megaspore single, chalazal, sporopollenin 0; gametophyte development initially endosporic, dependent on sporophyte, apical cell 0, rhizoids 0, development continuing outside the spore; male gametophyte with tube developing from distal end of grain, male gametes two, developing after pollination, with cell walls; female gametophyte initially syncytial, walls then surrounding individual nuclei; embryo cellular ab initio, endoscopic, plane of first cleavage of zygote transverse, suspensor +, short-minute, embryonic axis straight [shoot and root at opposite ends; plant allorhizic], cotyledons 2; plastid transmission maternal; ycf2 gene in inverted repeat, whole nuclear genome duplication [ζ - zeta - duplication], 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 trans- nad2i542g2 and coxIIi3 introns present.
ANGIOSPERMAE / MAGNOLIOPHYTA
Lignans, O-methyl flavonols, dihydroflavonols, triterpenoid oleanane, apigenin and/or luteolin scattered, [cyanogenesis in ANA grade?], lignin also with syringyl units common [G + S lignin, positive Maüle reaction - syringyl:guaiacyl ratio more than 2-2.5:1], 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, hypodermis suberised and with Casparian strip [= 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 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, overall growth ± diffuse, secondary veins pinnate, fine venation hierarchical-reticulate, (1.7-)4.1(-5.7) mm/mm2, vein endings free; flowers perfect, pedicellate, ± haplomorphic; protogynous; parts spiral [esp. the A], free, numbers unstable, development in general centripetal; P +, members each with a single trace, outer members not sharply differentiated from the others, not enclosing the floral bud; A many, filament not sharply distinguished from anther, stout, broad, with a single trace, anther introrse, tetrasporangiate, sporangia in two groups of two [dithecal], sporangium pairs dehiscing longitudinally by a common slit, ± embedded in the filament, walls with at least outer secondary parietal cells dividing, 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 lamellate only in the apertural regions, thin, compact, pollenkitt +; nectary 0; carpels present, superior, free, several, ascidiate, with postgenital occlusion by secretion, stylulus at most short [shorter than ovary], hollow, cavity not lined by distinct epidermal layer, stigma ± decurrent, carinal, dry, extragynoecial compitum +; 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, functional megaspore lacking cuticle; female gametophyte lacking chlorophyll, not photsynthesising, 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 grains land on stigma, bicellular at dispersal, mature male gametophyte tricellular, germinating in less than 3 hours, pollen tube elongated, unbranched, growing between cells, growth rate (20-)80-20,000 µm/hour, apex of pectins, wall with callose, lumen 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, cilia 0, siphonogamy; double fertilization +, ovules aborting unless fertilized; P deciduous in fruit; mature seed much larger than ovule when fertilized, small , dry [no sarcotesta], exotestal; endosperm +, cellular, development heteropolar [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; dark reversal Pfr → Pr; Arabidopsis-type telomeres [(TTTAGGG)n]; nuclear genome very small [1C = <1.4 pg, 1 pg = 109 base pairs], whole nuclear genome duplication [ε - epsilon - duplication]; protoplasm dessication tolerant [plant poikilohydric]; 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 + [with gelatinous fibres: lignified primary cell wall + thick gelatinous wall]; 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 +; sesquiterpene synthase subfamily a [TPS-a] [?level], 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 position]; pollen tube growth intra-gynoecial [extragynoecial compitum 0]; embryo sac bipolar, 8 nucleate, antipodal cells persisting; endosperm triploid.
[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; trichoblasts in atrichoblast [larger cell]/trichoblast cell pairs, the former further from apical meristem, in vertical files; endodermal cells with U-shaped thickenings; cork cambium in root [uncommon] superficial; stele oligo- to polyarch, medullated [with prominent pith], lateral roots arise opposite phloem poles; primary thickening meristem +; vascular bundles in stem scattered, (amphivasal), vascular cambium 0 [bundles closed]; 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; prophyll single, adaxial; leaf blade linear, main venation parallel, the veins joining successively from the outside at the apex, transverse veinlets +, unbranched [leaf blade characters: ?level], vein/veinlet endings not free, margins entire, Vorläuferspitze +, base broad, ensheathing the stem, sheath open, petiole 0, colleters + ["intravaginal squamules"]; inflorescence terminal, racemose; flowers 3-merous [6-radiate to the pollinator], polysymmetric, pentacyclic; P = T, each with three traces, median T of outer whorl abaxial, aestivation open, members of whorls alternating, [pseudomonocyclic, each T member forming a sector of any tube]; 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; pollen reticulations coarse in the middle, finer at ends of grain, infratectal layer granular; 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 small to medium sized [mean = 1.5 mg], testal; embryo long, cylindrical, cotyledon 1, apparently terminal, with a closed sheath, unifacial [hyperphyllar], both assimilating and haustorial, plumule apparently lateral; primary root unbranched, not very well developed, stem-borne 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 supervolute-curved or variants, (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; epidermis with bulliform cells [?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]: root hairs from unmodified rhizodermal cells, exodermal cells not dimorphic; outer integument 2(-3) cells across.
PANDANALES Berchtold & J. Presl Main Tree.
Anthers basifixed; nucellar cap +; endosperm type?, (reserves starch), embryo minute. - 5 families, 36 genera, 1345 species.
Age. Crown group Pandanales are estimated to be (96-)90, 84(-78) m.y.o. (Wikström et al. 2001), ca 114 m.y.o. (Janssen & Bremer 2004), (117-)82, 72(-65) m.y.o. (Bell et al. 2010), and (111-)103(-95) or (98-)91(-89) m.y. in Hertweck et al. (2015). Ages are ca 72.3 m.y.a. (Magallón et al. 2015: no Triuridaceae) or as little as ca 50 m.y. (Bremer 2000b), (130-)117(-116) m.y. in Merckx et al. (2008a) and 110-69 m.y. in Mennes et al. (2013, 2015).
Note: (....) denotes a feature common in the clade, exact status uncertain, [....] includes explanatory material. 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 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 are the not-so-trivial issues of how character states are delimited and ancestral states are reconstructed (see above).
Evolution. Divergence & Distribution. Stevenson et al. (2000) suggest other possible characters for the order and the 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. Hopwever, clarification of the position of Triuridaceae in particular is needed to understand morphological evolution in this clade (see Garay-Arroyo et al. 2012).
Chemistry, Morphology, etc. Rudall et al. (2005b) note that floral meristicity, usually not very variable in the monocots, varies considerably in Pandanales; general floral construction is rather labile here.
Some information on pollen morphology is taken from Grayum (1992); for pollen and tapetum, etc., see Furness and Rudall (2006a).
Phylogeny. For discussion on the relationships of Pandanales, see the Petrosaviales page.
The circumscription of Pandanales is somewhat unexpected, including as it does some of the most delicate (Triuridaceae) and most woody and robust (Pandanaceae) monocots. The phylogeny above is taken from Behnke et al. (2000, 2013), and especially Caddick et al. (2002a), Davis et al. (2004: Fig. 1) and Mennes et al. (2013), although even in the last study, quite comprehensive, the position of Stemonaceae was not very strongly supported. Janssen and Bremer (2003: Triuridaceae not included) suggested a somewhat different set of relationships. The [Pandanaceae + Cyclanthaceae] clade appears consistently and also has strong morphological support.
Triuridaceae often group with Pandanales in molecular analyses (e.g. Chase et al. 2000a: 18S rDNA; Graham et al. 2005), but they vary in their relationships within the order. Relationships in Hertweck et al. (2015) are [Velloziaceae [Triuridaceae [Stemonaceae...]]]. Morphological analyses even suggested that Triuridaceae were nested within Stemonaceae (Rudall & Bateman 2006), but without strong bootstrap support (50³%, hardly the robust placement claimed), and characters that supported this position included thick filaments, free carpels, and pollen morphology. However, recent analyses using plastomes, including the very small plastome of Sciaphila, yielded the rather well supported relationships in the tree below; only in parsimony analyses was a clade [Sciaphila + Xerophyta] obtained, and it had low support (Lam et al. 2015); sampling may be the only worry, 10 Pandanales were included in the study.
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! 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
Xeromorphic; roots with vessel elements with simple perforation plates, band of fibres in cortex; vessels in stem and leaf; stem cortex divided into three zones by bundles of fibres or fibrous sheath; 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 large; A borne in mouth of "hypanthium"; pollen grains bi- or tricellular; ovary inferior, placentae bifid, stalked-capitate, style long; ovules many/carpel, parietal tissue none; fruit dehiscing laterally, loculicidal; exotesta thick walled, endotegmen thin-walled, with phenolics/tanniniferous; aleurone cells with thick walls, endosperm with starch.
5[list]/240. South America and Africa-Madagascar to Arabia, China.
Age. The crown age of this family must be 115 m.y. or so (Mello-Silva et al. 2011).
1. Acanthochlamydoideae P. C. Kao
Caespitose rhizomatous herb; steroidal saponins +?; (velamen +), root stele tri- or tetrarch, not medullated; lateral roots arise opposite xylem poles; cauline vascular tissue aggregated in the centre of the stem, phloem dispersed among the xylem; scape with ca 6 central vascular bundles, leaf adnate to scape; raphides and tannin cells 0; palisade tissue 0; leaf blade with single vascular bundle, endodermis surrounding two back-to-back vascular strands; leaves spiral, ligule basal, surrounding stem, large; inflorescence scapose, compound-capitate; T ca 1/2 connate; anthers short, bisporangiate, ?thecae, monothecal, filaments short; septal nectaries 0; nucellar cap 0; exotestal cells evenly thickened, ± elongated; 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, Fruit.]
Synonymy: Acanthochlamydaceae P. C. Kao
2. Vellozioideae Rendle
Woody or herbaceous, adventitious roots often growing down through persistent leaf bases; biflavonoids + [Xerophyta]; (velamen +); tracheids in stem main conducting tissues; sieve tube plastids with angular crystals and other loosely-packed crystals; (vessels in leaves absent - Talbotia); 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, (blade abscising), vernation conduplicate-flat, midrib +, margins usu. spiny; inflorescences often single-flowered, bracteoles lateral; hypanthium +/0; flowers often violet, median T in outer whorl adaxial [e.g. Barbacenia], T largely free; (corona +, usu. adnate to adaxial A); A 6-many, not adnate to T), (3 or 6 fasciculate [A in fascicle connate], development within fascicles ± centripetal), filaments cylindrical, anthers long, (dithecal), (dorsifixed); (pollen in tetrads); septal nectaries +; stigmas large, erect or spreading, capitate; micropyle bi/endostomal, outer integument 2 cells across, inner integument 2 cells across, nucellar cap ?+, endothelium and funicular obturator +, suprachalazal tissue massive; chalazal cells several; fruit also poricidal or with intercostal apertures; exotesta with spiral/reticulate (0) thickenings, endotegmen with outer periclinal and anticlinal walls thickened (not); endosperm helobial, cells elongated, wall formation in small chalazal chamber precedes that in large micropylar chamber, (aleurone cell walls unthickened), 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.]
Age. Crown-group Vellozioideae have been dated to a mere ca 14 m.y.a. (Janssen & Bremer 2004: note sampling), or some 100 m.y.a. or so (Mello-Silva et al. 2011).
Synonymy: Barbaceniaceae Arnott
Evolution. Divergence & Distribution. Mello-Silva et al. (2011) interpreted the split of Acanthochlamys from the rest of the family and the other generic distributions in terms of drift-induced vicariant events.
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 (Cattai 2007); taxa like Triuridaceae and some Burmanniaceae also have non-medullated pith. The anatomy of the stem/rhizome of Acanthochlamys 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 (c.f. de Menezes et al. 2013). 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 and how the "foliar" bundles relates to the stele and to an inflorescence bract is unknown. The leaves of Acanthochlamys have a rather large basal adaxial ligule ensheathing the stem and lack axillary buds (de Menezes et al. 2013); the other genera have more simply 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), while in Acanthochlamys there appears to be two vascular strands surrounded by an endodermis in the foliar bundle (de Menezes et al. 2013). 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 terminal (Kubitzki 1998b), although this can be hard to make out; work on branching patterns would be useful. What is described here as the hypanthium in Velloziaceae may bear the same indumentum as is found on the petiole; assuming the traditional definition of a hypanthium, the perianth members here would usually be more or less free. 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 tepal-like (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. For the possibility of a chalazal haustorium in the embryo that develops from the antipodal cells or from chalazal nucellar tissue, see Sajo et al. (2013).
Additional information is taken from Ayensu (1973a), Kubitzki (1998b), and Behnke et al. (2000), all general, Williams et al. (1991: chemistry), Smith and Ayensu (1976: monograph - with anatomy - of New World taxa), Behnke et al. (20013: anatomy), de Menezes (1980: androecial evolution), Strassburg and de Menezes (2001: fruit and seed) and Sousa-Baena and de Menezes (2014: seed coat anatomy); for Acanthochlamys in particular, see Kao and Kubitzki (1998: much detail), 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, Acanthochlamys 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: see data matrix) found the relationships [Acanthochlamys [Xerophyta (inc. Talbotia) + the rest (support not strong)]] (see also Behnke et al. 2013: support much higher in Bayesian than ML analyses), and suggest a number of apomorphies for the main clades, although optimisation of some of them is difficult. For 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, yet Velloziaceae s.l. are well characterized.
For suggestions as to generic limits in the family, see Mello-Silva et al. (2011).
[Stemonaceae [Triuridaceae [Pandanaceae + Cyclanthaceae]]]: vessels also in stem, with scalariform perforation plates; (styloids +); flowers other than 3-merous; septal nectaries 0; placentation parietal, style 0, stigmas/stigmatic branches ± separate.
Age. The age of this node is estimated at ca 101.7 m.y. (Magallón & Castillo (2009), (84-)76, 66(-50) m.y. (Bell et al. 2010) or only ca 53.7. m.y.a. (Magallón et al. 2015).
STEMONACEAE Caruel, nom. cons. Back to Pandanales
Plant monopodial, (tuberous), with cataphylls, stem erect (twining); (unspecified saponins - Stemona), alkaloids with pyrrolo- or pyrido(1,2,-α)- azepine nucleus, +; stem vascular bundles in 1 or 2 rings, those of inner or only ring amphivasal; petiole bundles in arc; (styloids +); plant glabrous; leaves two-ranked or opposite, with petiole, blade and midrib, base not sheathing, midrib simple (not distinct), petiole bifacial [Croomia], cataphylls +, 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 , (inferior), placentae apical or basal, style branches long; 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].
Age. Crown group Stemonaceae are dated to ca 84 m.y. (Janssen & Bremer 2004).
Evolution. Pollination Biology & Seed Dispersal. At least some Stemonaceae are pollen flowers (Vogel 1981).
Myrmecochory is common in the family (Lengyel et al. 2010).
Chemistry, Morphology, etc. The distinctive alkaloids found in Stemonaceae with their pyrrolo- or pyrido(1,2,-α)-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 cataphylls, 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. However, Lam et al. (2015: plastome analyses) found the relationships [Pentastemona [Stemona + The Rest]].
Pentastemona can be briefly characterised as follows: Succulent monopodial herb; cataphylls 0; hairs uniseriate; stomata para- or tetracytic; leaves spiral, with compound midrib, sheath ?closed; inflorescences (branched) racemose; flowers 5-merous, perianth tube long to short; A 5, connate into a fleshy ring, basally adnate to T and connectives apically adnate to stigmas; pollen inaperturate, atectate; [G 3], inferior, placentation parietal, many ovules/carpel, stigmatic lobes well developed; fruit a berry; seed arillate; sarcoexotesta +, endotesta with massive U-shaped thickenings, producing ridges; seedling?
Synonymy: Croomiaceae Nakai, Pentastemonaceae Duyfjes, Roxburghiaceae Wallich
[Triuridaceae [Pandanaceae + Cyclanthaceae]]: ?
Age. The stem node of Triuridaceae has been dated to to 86.3 m.y.a. based on the New Jersey fossil Mabelia connatifila (Isles et al. 2015).
TRIURIDACEAE Gardner, nom. cons. Back to Pandanales
Plant myco-heterotrophic, echlorophyllous; chemistry?; root hairs 0-many; vessels 0; root pith not medullated; 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 grains tricellular, 15-25 µm across, inaperturate, surface gemmate, gemmae with protruberances or spines; G 10-many, separate, plicate, styles solid, no transmitting tissue, stigma penicillate to smooth, ?dry; ovules basal, parietal tissue none, nucellar cap 0, endothelium, hypostase +; seeds endotestal, inner cuticle 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).
Age. The age of crown-group Triuridaceae is estimated at 90-50 m.y. (Mennes et al. 2013).
Despite the delicate nature of plants of this family, fossil flowers of Triuridaceae (two genera) have been reported from ca 90 m.y.o. 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 (Rudall 2003b; Friis et al. 2011).
1. Kupeaeae Cheek
Root hairs none; inflorescence a spike; plant dioecious; flower monosymmetric; T 4, (basally connate), with a single trace [Kupea], apex acute, (bifid); staminate flowers: (bract adnate to flower - Kupea); A 4, anther dehiscence transverse; pollen ca 25 µm across; carpellate flower: style (sub)terminal; ovules 2/carpel, hemitropous to campyltotropous; fruit indehiscent; ?endosperm.
2/3. Africa; Cameroon and Tanzania.
[Sciaphileae + Triurideae]: ovule 1/carpel.
2. 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 amoeboid; pollen (monosulcate - Sciaphila), 24-40 µm across; style gynobasic; 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].
3. 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; carpellate flowers: carpel development centrifugal [Triuris], style (sub)terminal; 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.]
Synonymy: Lacandoniaceae E. Martínes & Ramos
Evolution. Divergence & Distribution. Mennes et al. (2013) found long branch lengths within Triuridaceae, and noted that these, along with the age of the family and its myco-heterotrophic life style, made its morphological distinctiveness comprehensible.
Rübsamen-Weustenfeld (1991) lists other characters, especially of endosperm, embryo size and seed anatomy, that separate Sciaphileae and Triurideae; 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). Interestingly, the carpels still develop after the stamens, despite their reversed positions (Garay-Arroyo et al. 2012), and Endress (2014) made an ingenious suggestion that the relative position of the two is normal, only appearing to have been thrown off because of the distortion at the floral apex caused by the development of numerous carpels. It has been suggessted that the recognition of Lacandonia may make Triuris paraphyletic (Vergara-Silva et al. 2003); if this relationship is confirmed (it was not by Mennes et al. 2013), the morphological context for an explanation of the distinctive floral construction of Lacandonia becomes very specific indeed.
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).
Genes & Genomes. For the very small chloroplast genome of Sciaphila densiflora with its 28 functional genes, see Lam et al. (2015); it is largely colinear with that of Carludovica, over seven times its size.
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 in 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 from 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). Hooker (1859) noted that the ovules were anatropous and unitegmic. Although some Triuridae have tetrasporic embryio sacs of the Fritillaria-type, ordinary monosporic Polygonum-type embryo sacs have also 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?), is reflected in their being more or less winged on one side.
Additional information: For general information, Rübsamen-Weustenfeld (1991) and Maas-van der Kamer and Weustenfeld (1998), for pollen, etc., Furness et al. (2002a), for ovule and seed, see Johow (1889), and for carpels, etc., see Igersheim et al. (2001).
Phylogeny. In morphological analyses Kupea was sister to the rest of the family and Sciaphileae were paraphyletic (Rudall & Bateman 2006: Kihansia not included). The three tribes above were recovered as monophyletic in the four-gene study by Mennes et al. (2013), but inclusion of additional taxa with fewer than three genes suggested that Sciaphileae, and in particular Sciaphila, were paraphyletic, Sciaphileae and Trirideae together being sister to Kupeaeae (see also Mennes et al. 2015).
Classification. For tribes, I follow Rübsamen-Weustenfeld (1991) and Cheek (2003a).
Previous Relationships. Triuridaceae have often been associated with Alismataceae and relatives, all having separate carpels and so assumed to be primitive.
[Pandanaceae + Cyclanthaceae]: stem vascular bundles compound; styloids +; stomata tetracytic, subsidiary cells with oblique cell divisions; leaf blades ± plicate-appearing; inflorescence bracts conspicuous, inflorescence a dense spike or head [a spadix], inflorescence bracts coloured or not; flowers sessile, in a spiral; flowers imperfect; staminate flowers: stamens usu. several-many; pollen porate; pistillode +; carpellate flowers: staminodes +; ovules apotropous, with radiating subepidermal nucellar/chalazal cells; 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.
Age. The divergence between the two families has been dated to (74-)68, 66(-60) m.y. (Wikström et al. 2001), ca 98 m.y. (Janssen & Bremer 2004), (71-)52, 47(-31) m.y. (Bell et al. 2010), and (139.3-)86, 81(-49) m.y. (Gallaher et al. (2014).
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. See Carlquist (2012a) for xylem anatomy.
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
Plant woody, habit various, trees, shrubs, or climbers with roots from leaf axils, rhizomes 0; vessel elements also in leaf; 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, margins 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 - Pandanus), (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.]
Age. Crown group Pandanaceae began to diverge ca 51 m.y.a. (Janssen & Bremer 2004), 95 m.y.a. or more (Callmander et al. 2003), or (101-)65, 58(-38.3) m.y. (Gallaher et al. 2014).
The pollen genus Pandaniidites is known from North America where it spans the Cretaceous-Caenozoic boundary and has been found in rocks up to 70 m.y. old (Hotton et al. 1994). However, since Pandaniidites is associated with flowers of Limnobiophyllum it is to be assigned to Araceae-Lemnoideae (Stockey et al. 1997; Stockey 2006), not Pandanaceae. Fossils of Pandanus around 80 m.y.a. are reported from Austria (Kvacek & Herman 2004), but Gallaher et al. (2014) are sceptical of the identity of most other fossils attributed to the family.
Evolution. Divergence & Distribution. Callmander et al. (2003) discussed the biogeography of the family in the context of the Gondwanan break-up, which sets up rather discordant estimates for the age of the family (see above). However, Gallaher et al. (2014) present revised age estimates and suggest that dispersal is more likely to explain the Gondwanan elements of their current distribution, indeed, given the Laurasian fossils of the family, they thought that Pandanaceae might even originate there. Diversification within the speciose Pandanus itself started a mere (20.2-)12.9, 11.5(-5.4) m.y.a., and water dispersal in particular is discussd as facilitating the current wide distribution of the genus, with the Pandanus tectorius complex achieving the range of almost the entire family within the last 6 m.y. (Gallaher et al. 2014).
Pollination Biology & Seed Dispersal. Bat pollination may be quite common (Fleming et al. 2009). 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).
For dispersal in Pandanaceae, predominantly by water or animals, see Gallaher et al. (2014).
Chemistry, Morphology, etc. Since there is no perianth, the position of the ovary is 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 they may face ad- or abaxially (c.f. Cercidiphyllum), sometimes within a single floral unit (Stone 1968). Fagerlind (1940a) suggested that Pandanus did not always have a bisporic embryo sac. The embryo sac of Pandanus appears to have extra antipodal cells, however, these come from the nucellus (see Maheshwari 1955 for discussion).
Some information is taken from Dahlgren et al. (1985) and Stone et al. (1998), both general, see also Zimmermann et al. (1974: vascular organization in the stem), Strömberg (1956) and Cheah and Stone (1975), both embryology, Hotton et al. (1994: pollen), and Huynh (2001: Sararanga).
Phylogeny. For early studies on 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 [Sararanga [Freycinetia [Acrostigma clade, core Pandanus, Martellidendron]], and these were similar in Gallaher et al. (2014), although there was little support for Benstonea as sister to Pandanus in the chloroplast data alone, 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... It would be nice to know what the intrafamilial relationships are.
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
Large herbs; vascular tracheids or vessels [?type] in root and leaf; petiole bundles scattered; mucilage cells +; leaves spirally two-ranked, petiolate, blade vernation plicate or variants, Vorläuferspitze 0 [in elaborated leaves], petiole ± terete; plant monoecious; inflorescence (branched), spadiciform; flowers with mucilage canals; staminate flowers: P 0; A connate basally; pollen lacking endexine lamellae; carpellate flowers: ovules many/carpel, (epitropous), outer integument 3-5 cells across, parietal tissue none, nucellar epidermal cells radially elongated, (hypostase +), (postament +); endosperm helobial, embryo short; collar rhizoids +.
12/225: Two groups below. Central and tropical South America (map: from Harling 1958; fossil Cyclanthus [blue] from Smith et al. 2009).[List]
Age. Crown group Cyclanthaceae are dated to (55-)49, 45(-39) m.y.a. (Wikström et al. 2001), ca 77 m.y.a. (Janssen & Bremer 2004), (50-)33, 30(-14) m.y. (Bell et al. 2010), and (72.7-)45, 42.3(-22.9) m.y. (Gallaher et al. 2014).
Cyclanthus has quite recently been identified from the European Eocene sediments ca 47 m.y.o.; the seeds had previously been misidentified as Scirpus (Smith et al. 2008; see also Collinson et al. 2012; Smith 2013; Isles et al. 2015). This questions some of the ages that have been suggested for the family.
1. Cyclanthoideae Burnett
(Growth monopodial); root with multiseriate circum-cortical sclerenchymatous tissue; subepidermal sclereids +; druses +, mucilage cells in inflorescence only, tanniniferous cells 0, non-articulated laticifers +; lysigenous air spaces with transverse septae +; leaf blade deeply bifid [by tearing of tissues], vernation modified plicate [plicate across principal veins], blades costate [costae almost to the apex]; inflorescence with whorls of staminate and carpellate "flowers"; staminate flowers: A in 4 rows per whorl; carpellate flowers: P +, small; staminodes +; G, ovary cavity with closely-set placentae; ovules endostomal, outer integument ca 2 cells across, inner integument ca 3 cells across, nucellar cap 0, 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.]
2. Carludovicoideae Harling
Also epiphytes, and/or lianes and vines; root (with multiseriate circum-cortical sclerenchymatous tissue - Schultesiophytum), (not medullated, centre portion occupied by intermixed xylem and phloem); (stem cork subepidermal or outer cortical); (styloids +); mucilage and tanniniferous cells +; leaves (spiral), elliptic to ± 3-partite, 1- or 3-costate [lateral costae short], margins usu. deeply dentate, (hastula +); inflorescences (axillary); staminate flowers: A ca 10-many, filaments swollen basally, staminodia abaxial, glandular; carpellate flowers: 4(-8)-merous; staminodes long-filiform, opposite P; G 4, ± inferior, alternating with P, (placentae apical); ovules bistomal, outer integument ca 3 cells across, inner integument ca 2 cells across, nucellar cap 2-3 cells across; 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. The discovery of Cyclanthus in the European Eocene (Smith et al. 2008; see also Collinson et al. 2012; Smith 2013) changes how one thinks of the evolution and distribution of the family. Cyclanthus is common there and may even be a diagnostic element of the vegetation - along with Nypa.
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. Leaf developmentis rather like that of broad-leaved angiosperms, a Vorläuferspitze was evident only in leaves of Carludovica palmata developing early in the ontogenetic sequence (Wilder 1976, 1981a). Leaf insertion can change from spiral to two-ranked or two-ranked to spiral during the growth of the plant (Wilder 1981a). Further information on the morphology and vernation of leaves is given by Wilder (1981b) and on growth habit by Wilder (1992b).
In staminate flowers, both perianth and stamen number may increase. There are varying interpretations of the staminate flowers of P in one (two) whorls, 6+ (-30), with abaxial glands, or P 0, staminodia abaxial, glandular (Sajo et al. 2014). The gynoecium/carpellate flowers of Cycalanthus are shown as having the gynoecium immediately surrounded by staminodes and then by perianth lobes; stamens/staminate flowers alternate with the gynoecium (Sajo et al. 2014). 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 much information on just about everything, see Harling (1958) and Harling et al. (1998), for anatomy, see Tomlinson and Wilder (1984) and Wilder (1986, 1992a and references), for embryology, see Harling (1946), and for seeds of Cyclanthus, see Smith et al. (2008).
Phylogeny. For a detailed morphological phylogeny of the family, see Eriksson (1994).