EXTANT SEED PLANTS

Plant woody, evergreen; nicotinic acid metabolised to trigonelline; primary cell walls rich in xyloglucans and/or glucomannans, 25-30% pectin [Type I walls]; lignins rich in guaiacyl units; true roots present, xylem exarch; shoot apical meristem complex; arbuscular mycorrhizae +; stem with ectophloic eustele, endodermis 0, xylem endarch; vascular tissue in t.s. discontinuous by interfascicular regions; vascular cambium + [xylem ("wood") differentiating internally, phloem externally]; wood homoxylous, tracheids +; tracheid/tracheid pits circular, bordered; sieve tube/cell plastids with starch grains; phloem fibers +; stem cork cambium superficial, root cork cambium deep seated; nodes ?; leaf vascular bundles collateral; leaves spiral, simple, axillary buds?, prophylls [including bracteoles] two, lateral; plant heterosporous, sporangia eusporangiate, on sporophylls, sporophylls aggregated in indeterminate cones/strobili; true pollen [microspores] +, mono[ana]sulcate, pollen exine and intine homogeneous, ovules unitegmic, crassinucellate, megaspore tetrad tetrahedral, only one megaspore develops, megasporangium indehiscent; male gametophyte development endo/exosporic, gametes two, with cell walls; female gametophyte endosporic, initially syncytial, walls then surrounding individual nuclei; seeds "large", first cell wall of zygote transverse, embryo straight, endoscopic [suspensor +], short-minute, with morphological dormancy, white, cotyledons 2; plastid transmission maternal; two copies of LEAFY gene, PHY gene duplication, mitochondrial nad1 intron 2 and coxIIi3 intron present.

MAGNOLIOPHYTA

Plant woody, evergreen; lignans, O-methyl flavonols, dihydroflavonols, triterpenoid oleanane, non-hydrolysable tannins, quercetin and/or kaempferol +, apigenin and/or luteolin scattered, cyanogenesis via tyrosine pathway, lignins derived from both coniferyl and sinapyl alcohols, containing syringaldehyde [in positive Maüle reaction, syringyl:guaiacyl ratio less 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; stem with 2-layered tunica-corpus construction; wood fibers and wood parenchyma +; reaction wood ?, with gelatinous fibres; starch grains simple; primary cell wall mostly with pectic polysaccharides; tracheids +; sieve tubes eunucleate, with sieve plate, companion cells from same mother cell that gave rise to the tube, the sieve tube with P-proteins; nodes unilacunar; stomata with ends of guard cells level with aperture, paracytic; leaves with petiole and lamina [the latter formed from the primordial leaf apex], development of venation acropetal, 2ndary veins pinnate, fine venation reticulate, vein endings free; flowers perfect, polysymmetric, parts spiral [esp. the A], free, numbers unstable, P not differentiated, outer members not enclosing the rest of the bud, A many, development centripetal, with a single trace, introrse, filaments stout, anther ± embedded in the filament, tetrasporangiate, dithecal, with at least outer secondary parietal cells dividing, each theca dehiscing longitudinally by action of hypodermal endothecium, endothecial cells elongated at right angles to long axis of anther, tapetum glandular, binucleate, microspore mother cells in a block, microsporogenesis successive, pollen subspherical, binucleate at dispersal, trinucleate eventually, tectum continuous, endexine compact, lamellate only in the apertural regions, pollen tube elongated, with callose plugs, penetrating between cells, growth rate moderate, siphonogamy occuring, nectary 0, G free, several, ascidiate, with postgenital occlusion by secretion, few [?1] ovules/carpel, ovules marginal, anatropous, bitegmic, micropyle endostomal, integuments 2-3 cells thick, megasporocyte single, megaspore lacking sporopollenin and cuticle, chalazal, female gametophyte ?type, stylulus short, stigma ± decurrent, wet [secretory]; P deciduous in fruit; seed exotestal; double fertilisation +, endosperm ?diploid, cellular [first division oblique, micropylar end initially with a single large cell, chalazal end more actively dividing], copious, oily and/or proteinaceous, embryo cellular ab initio; germination hypogeal, seedlings/young plants sympodial; Arabidopsis-type telomeres [(TTTAGGG)_n]; whole genome duplication, 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 PHYA/PHYC gene pairs.

Possible apomorphies are in bold. Note that the actual level to which many of these features, particularly the more cryptic ones, should be assigned is unclear, because some taxa basal to the [magnoliid + monocot + eudicot] group have been surprisingly little studied. Furthermore, details of relationships among gymnosperms will affect the level at which some of these characters are pegged.

NYMPHAEALES [AUSTROBAILEYALES [[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]]]]: vessels +, elements with scalariform perforation plates; pollen tectate-columellate, tectum reticulate [perforated]; nucleus of egg cell sister to one of the polar nuclei; ?genome duplication; "DEAER" motif in AP3 and PI genes lost, gaps in these genes.

COMMELINIDS   Back to Main Tree

Unlignified cells walls with UV-fluorescent ferulic and coumaric acids; (vessels in stem and leaves); SiO₂ bodies in leaves; stomata para- or tetracytic, (cuticular waxes as aggregated rodlets [looking like a scallop of butter]); inflorescence bracteate; (P fully bicyclic [= K + C]) [A adnate to C/inner P], pollen starchy; embryo short, broad.

The stem group of commelinids is dated to ca 122 million years before present, divergence within it begins ca 120 million years before present (Janssen & Bremer 2004) - or the figures are 107-98, 99-91 (Arecaceae sister to rest) and 94-86 million years before present respectively (Dasypogonaceae sister to remainder: Wikström et al. 2001), or ca 116 million years before present, Arecaceae and Dasypogonaceae diverging almost immediately, and Poales and [Commelinales = Zingiberales] within 4 my (Bremer 2000b). Larval food plants of Nymphalidae-Morphinae and Satyrinae are widely distributed in this group (Ehrlich & Raven 1964), as are those of Chrysomelidae-Hispinae and -Criocerinae (Jolivet 1988; Schmitt 1988; Vencl & Morton 1999), although these latter are also found in some other monocots (as well as Boraginaceae, Solanaceae, Convolvulaceae and Asteraceae, in particular, among the core eudicots). However, it is unclear if Criocerinae are in a clade immediately related to Hispinae and related monocot-eating beetles, or not (cf. Wilf et al. 2000 and Gómez-Zurita et al. 2007). The beetle larvae eat between the veins!

Silicon concentrations are generally high, although not of course in groups that do not have SiO₂ bodies, although even there they are not always high (Ma & Takahashi 2002). Lignins from Poaceae and Arecaceae (and elsewhere?) have p-coumaryl alcohol as well as coniferyl and sinapyl monomers (Siegler 1998). Although vessels in the stem and leaves are common (Wagner 1977), it may well be incorrect to treat this as a synapomorphy. In those few commelinids whose floral development has been studied in detail, expression of the B-class gene orthogue of PISTILLATA seems to be restricted to the stamens/staminode and petals (Adam et al. 2007); this may be connected with the fully bicyclic nature of the perianth found in many members of this clade. In some of the few other monocots studied, development may be somewhat different. Starch-containing pollen is common, but has not been found in Hanguanaceae or Dasypogonaceae (only one species of the latter examined) and in some species of Haemodoraceae, Bromeliaceae, etc. Broad embryos may be a synapomorphy at about this level.

Commelinids are well supported in molecular studies (e.g. Graham et al. 2006, and references), and they have morphological support as well, but relationships between the main groups within them are unclear. Hilu et al. (2003: matK) have recently suggested that Poales may be sister to other commelinids, but the posterior probabilities are low. Neyland (2002b: 26s rDNA) found that Dasypogonaceae were strongly associated with Restionaceae and other families (Poales), but this particular relationship is not suggested by other molecular data, nor does it appear in morphological analyses. However, recent work using multi-gene data sets is not linking them with Arecales, even if where they end up has no strong support (see Chase et al. 2006 - near Poales; Graham et al. 2006 - near [Commelinales + Zingiberales], itself a well supported group). Arecales sometimes appear as sister to Poales (e.g. Graham et al. 2006), but with very weak support. Although Givnish et al. (1999) made a classification of four superorders and 10 orders for the commelinids based on a rbcL phylogeny, A.P.G. has recognised many fewer orders. These are generally well supported and stable clades, although as noted relationships between them for the most part have little support (see also Chase et al. 2000a). See also Commelinales, Zingiberales, and Poales.

Some morphological information about the commelinids is summarised by Givnish et al. (1999).

Unplaced:  Back to Main Tree

DASYPOGONACEAE Dumortier

Plant non-mycorrhizal; rhizomatous or arborescent (extensive primary thickening); vessels only in roots; 2 peripheral phloem strands in foliar bundles; leaves spiral, (serrulate), sheath well developed, bases persisting; P dry, septal nectaries +, 1 ascending ovule/carpel, micropyle bistomal; seeds rounded, testa pale yellow; endosperm type?.

4[list]/16. West Australia, Victoria. [Photo - Habit] [Photo - Flowers]

Dasypogon + Calectasia

Hairs branched; (chelidonic acid + - Dasypogon); raphides only in flowers; SiO₂ epidermal; stomatal accessory cell ontogeny odd; leaf bundle girders 0; inflorescence capitate, flowers in clusters or single; T, or outer whorl only, connate, floral tube short, A adnate to base of T (porose - Calectasia); fruit indehiscent; tegmen collapsing, massive storage nucellus [below embryo sac]; n = 7, 9; cotyledon not photosynthetic, mesocotyl and coleoptile +.

2/14. S.W. Australia, Victoria (Map: from Barrett & Dixon 2001; FloraBase 2004).

The two genera may have diverged 49-41 million years before present (Wikström et al. 2001).

Calectasia has a 1-locular ovary; some species have stilt roots. For Calectasia, see Barrett and Dixon (2001).

Synonymy: Calectasiaceae Endlicher

Kingia + Baxteria

Raphides 0; leaf bundle girders originating in mesophyll; inflorescence capitate or single-flowered [Baxteria], surrounded by bracts, stalk bracteate; T (large - Baxteria) free, A ± adnate to base, pollen extended sulcate-unipantocolpate; fruit indehiscent or explosively septifragal [Baxteria]; n = 7; seedling?

2/2. S.W. Australia (Map: from FloraBase 2004).

Storage nucellus?

Synonymy: Baxteriaceae Takhtajan, Kingiaceae Endlicher

In Kingia the apical meristem is depressed, as in Arecaceae, and the plant is also monopodial; adventitious roots grow down to the ground in persistent sheathing leaf bases.

Stem group Dasypogonaceae are dated to ca 119 million years before present, divergence within crown group Dasypogonaceae to ca 100 million years before present (Janssen & Bremer 2004: they place Dasypogonaceae rather near the base of the commelinids).

Dasypogonaceae are often linked with other xeromorphic monocots from Australia such as Xanthorrhoeaceae and Laxmanniaceae (previously Lomandraceae), as in Takhtajan (1997); the two latter families are in Asparagales.

Information is taken from Chanda and Ghosh (1976: pollen), Rudall and Chase (1996) and Clifford et al. (1998b).

Synonymy: Dasypogonales Reveal

ARECALES Bromhead  Main Tree, Synapomorphies.

Plant woody, usu. monopodial; vessels also in stem and leaf; cuticular waxes as aggregated rodlets, stomata tetracytic; leaves spiral, petiolate, reduplicate-plicate, pinnately (palmately) pseudocompound or deeply divided; flowers ± sessile, septal nectaries +, 1 apotropous ovule/carpel.

ARECACEAE Schultz-Schultzenstein, nom. cons.//Palmae Jussieu, nom. cons. et nom. alt.   Back to Arecales

Stem unbranched or not; flavonoid sulphates abundant; SiO₂ bodies sometimes hat-shaped, often spiny-verrucate, esp. associated with fibers strands or vascular bundles; leaf with closed sheath; plant often monoecious; inflorescences with bicarinate prophyll, on branches prophylls lateral [hence ultimate units are cincinni]; fruit a (dry) berry or drupe; seed 1(-3), rounded; endosperm with hemicellulose; cotyledon not photosynthetic, collar short (with roots), primary root strong, branched.

189[list]/2361 - five groups below. Humid tropics and subtropics (warm temperate), Africa is relatively depauperate. [Photo - Flowers, Fruits.]

1. Calamoideae Beilschmied

SiO₂ bodies ± spherical; internodes usu. well-developed; (inflorescence axes adnate to the internode above); breeding system various, flowers in diads; C valvate, (pollen equatorially disulcate - Calameae), ovule basal, epitropous [funicle twisted], styles +; G covered by reflexed scales, endocarp thin (thick - Eugeissonia); seeds 1-3, sarcotesta usually thick; n = 13, 14.

21/: Calamus (400), Daemonorops (115). Tropical, but esp. Sri Lanka to West Samoa and Fiji (Map: from Uhl & Dransfield 1987).

For morphology, phylogeny and classification in Calamoideae, see Baker et al. (1999b, 2000a, b, c).

Synonymy: Calamaceae Perleb, Lepidocaryaceae O. F. Cook

Nypoideae [Coryphoideae + Ceroxyloideae + Arecoideae]: ?

2. Nypoideae Griffith

Branching dichotomous; inflorescence axes adnate to the internode above, with staminate spike and carpellate heads; staminate flowers: P undifferentiated, A 3, opposite outer P, connate, extrorse, pollen zonasulcate, pistillode 0; carpellate flowers: staminode 0, G 3 (4), margins conduplicate, ovule [position?], outer integument 10 cells across, placentation laminar to submarginal; n = ?17.

1/1: Nypa fruticans. Malesia (Bengal to Queensland) (Map: from Uhl & Dransfield 1987).

Nypa fossils in the early Tertiary ± are world-wide, including Tasmania, England (the London Clay flora), etc.

For information, see Uhl (1972) and Uhl and Dranfield (1987).

Synonymy: Nypaceae Le Maout & Decaisne

Coryphoideae + Ceroxyloideae + Arecoideae: microsporogenesis simultaneous.

3. Coryphoideae Burnett

(SiO₂ bodies ± spherical); leaves palmate or costapalmate (pinnate), induplicate; inflorescence various, (terminal; adnate to the internode above; plant monoecious - Caryotinae; flowers in triads); C often valvate, microsporocyte with callose ring [not Caryota, Bismarckia], G free, or connate by style, or style +, with 3 [Coryphinae] or 1 [Sabalinae] stylar canals, or style 0 [Caryoteae].

45/ : Coccothrinax (50). Pan tropical (to warm temperate), fewer in South America (Map: from Uhl & Dransfield 1987).

Coryphoideae include Arecoideae-Caryoteae, previously placed in Arecoideae (Uhl and Dransfield 1987); see also Dransfield et al. (2008) for a phylogeny).

Synonymy: Borassaceae Schultz-Schultzenstein, Coryphaceae Schultz-Schultzenstein, Phoeniciaceae Burnett, Sabalaceae Schultz-Schultzenstein

4. Ceroxyloideae Drude

SiO₂ bodies ± spherical; flowers solitary along the rhachis, (K and C elongate); (seeds more than 3).

8/42. Mostly Central and W. South America, also N.E. Australia, Madagascar, Florida and the Antilles (Map: from Uhl & Dransfield 1987).

This includes Phytelephantoideae (Dransfield et al. 2005). The scattered and apparently ancient Gondwanan distribution of the subfamily is probably best explained by several mid-Tertiary trans-oceanic dispersal events (Trénel et al. 2007). Phytelephas and its relatives have 4-merous flowers with up to 1000 centrifugal stamens (Palandra) and 10 carpels; Palandra also has monopodial flower clusters, unique in the family.

Synonmy: Phytelephaceae Perleb,

5. Arecoideae Burnett

Inflorescence with prophyll and bract(s); plant usually monoecious with flowers in triads [central flower carpellate, lateral flowers staminate] or dioecious with flowers in monopodial inflorescences; (1 G fertile), styles + (style +, short or long); n = 16.

112/ : Bactris (240), Dypsis (140), Pinanga (120), Chamaedorea (110), Geonoma (75), Desmoncus (65<), Areca (60), Astrocaryum (50). Pantropical, the most diverse subfamily in South America (Map: from Uhl & Dransfield 1987).

This clade is the Arecoideae of Uhl and Dransfield (1987), but minus Caryoteae, and it also includes Ceroxyloideae-Hyophorbeae (Hahn 2002b; also Baker et al. 1999a), basically, the arecoid line of Moore (1973: see Dransfield et al. 2005).

See Gunn (2004) for a phylogeny of Cocoeae; Lewis and Doyle (2002) and Baker et al. (2006) for a phylogeny of Areceae; Norup et al. (2006) for generic limits in Areceae, most of which have a distinctive crown shaft (tribal apomorphy). Cuenca and Asmussen-Lange (2007) and Cuenca et al. (2007, 2008) discuss the phylogeny and biogeography of the largely New World understory Chamaedoreeae (for the phylogeny of Chamaedorea, see Thomas et al. 2006). Hyophorbe is disjunct on the Mascarenes, and may have radiated there on islands that are now submerged, hopping from island to island (Cuenca et al. 2007: see Myrtaceae, Begoniaceae, and Sapotaceae for similar island-hopping behaviour).

Synonymy: Acristaceae O. F. Cook, Ceroxylaceae O. F. Cook, Chamaedoraceae O. F. Cook, Cocosaceae Schultz-Schultzenstein, Geonomataceae O. F. Cook, Iriarteaceae O. F. Cook & Doyle, Malortieaceae O. F. Cook, Manicariaceae O. F. Cook, Pseudophoeniciaceae O. F. Cook, Synechanthaceae O. F. Cook

• Arecaceae can be recognised by their woody stems, large, tough, petiolate leaves with plicate and often apparently compound blades, axillary inflorescences (but Corypha, etc.!) with numerous flowers, and 1-seeded fruits. Cyclanthaceae can be similar vegetatively, but their petioles are usually less woody and the leaf never has a hastula, an adaxial flap-like structure at the apex of the petiole.

Stem group Arecaceae are dated to ca 120 million years before present, divergence within the crown group to ca 110 million years before present (Janssen & Bremer 2004), or the dates are 99-91 and 73-63 million years before present respectively (Wikström et al. 2001); palm pollen and/or wood seems quite common and widely distributed in the later Cretaceous (Burnham & Johnson 2004). Seed size in Arecaceae seems to have undergone a notable increase, probably associated with the adoption of the tree habit by the clade (Moles et al. 2005a). Genes in all three compartments apparently evolve slowly in this group (Wilson et al. 1990; Baker et al. 2000a, 2000b), although perhaps not that much more slowly that in a number of other monocots, especially in monocots that are other than commelinids (Graham et al. 2005); more accurately, perhaps, there was an increase in the rate of change within some commelinids, some of the Poales being spectacular examples.

Riodininae-Riodininae larvae may be found on Arecaceae. Pollination is predominantly by insects, whether beetles (mainly Nitidulae and Cuculionidae-Derelomini), flies, which may visit especially understory palms, and bees (Henderson 1986). Dufaÿ et al. (2003) found that volatiles produced by the leaves of Chamaerops humilis attracted its weevil pollinator. Thermogenesis has been detected in the flowers of some Arecaceae (Seymour 2001), and the family is another example of the combination shaded conditions, net-veined leaves and fleshy fruits that has evolved several times in monocots (Givnish et al. 2005, 2006b).

Most palms that have aerial stems undergo a period of establishment growth as seedlings during which the apical meristem becomes gradually larger; only when it has reached adult size does elongation growth of the trunk occur. In general, seedling morphology is very variable within Arecaceae (Tillich 2007). Iriarteeae (Arecoideae) are an exception. Here the apical meristem in the above-ground stem becomes gradually larger, and so the trunk becomes gradually stouter; massive prop roots from the lower part of the trunk stabilise the otherwise highly unstable structure. Note that xylem and phloem tissues remain functional during the life of the adult plant, i.e. for some hundreds of years. According to Arber (1925), the vascular bundles are not amphivasal. "Leaflets" of induplicate leaves are V-shaped in cross section, those of reduplicate leaves are inverted V-shaped. "Leaflets" of induplicate leaves are V-shaped in cross section, those of reduplicate leaves are inverted V-shaped. The leaves of palms are simple. The deep lobes in simple palm leaves, and the leaflets in apparently compound leaves, are the result of cell death. More particularly, what goes on is rather like abscission, although nothing (apart, sometimes, from the leaf margin) falls off. The parts that will separate first become thin, then separate, and then the zone of separation is protected by processes lignification, suberisation, etc. (Nowak et al. 2007). In a number of palms thin "reins" can be found hanging down from the sides of the leaves; these represent the leaf margins of the originally simple leaf. Fibers found at the bases of the leaves are produced by the decay of the sheaths, while the spines found on so many palms are produced in various ways (modified leaflets, adventitious roots, partly detaching outer parts of the stem, etc.).

Arecaceae have the largest leaf - Raphia sp., ca 25 x 3 m; the largest inflorescence - Corypha umbraculifera, ca 7.5 m long with some 10,000,000 flowers and 5280 m of flower-bearing axes (Tomlinson & Soderholm 1975); the largest seed - Lodoicea maldavica, to 50 cm long and 15-30 kg, which produces the longest cotyledon, or, strictly speaking, an apocole or elongated, unifacial, non-photosynthetic part opf the cotyledonary hyperphyll - "several yards", "twelve feet or more" (Thiselton-Dyer 1910); the oldest functioning xylem elements and sieve tubes - the oldest palm is hundreds of years old, and there is no secondary thickening (see Parthasarathy 1974 for phloem development; Tomlinson 2006b for xylem function and the length of stem [Calamoideae were the focus], age itself of the stem did not shape the discussion).

Microsporogenesis is simultaneous in some Coryphoideae and Arecoideae (Harley 1999a; Sannier et al. 2006). The flower in general (e.g. Rudall et al. 2003b) and pollen in particular (see Harley 1999b; Harley & Baker 2001) is remarkably variable. The stamens are never adnate to the corolla/inner tepals in staminate flowers, although in carpellate flowers of Roystonea the corolla has a broad staminal cup at the base. In Voaniola n = 298 or more.

The classification of Arecaceae above follows that of Dransfield et al. (2005). Nypoideae + Calamoideae (strong support) + the rest of the family (moderate support) formed a trichotomy in a three-gene study by Asmussen et al. (2000); other characters supported these general relationships. However, other work suggested that details of the relationships of Nypoideae and Calamoideae to the rest of the family were unclear, Calamoideae probably being sister to all other Arecaceae, and some morphological groupings were not supported by molecular data (Hahn 2002a, b; see also Baker et al. 1999a; Asmussen & Chase 2001; Lewis & Doyle 2001). Asmussen et al. (2006: very good generic-level sampling, four genes) have clarified this confusion and present the rather well supported set of relationships summarized in the tree here; those parts less well supported (the monophyly of Ceroxyloideae and Arecoideae) are strongly supported by low copy nuclear DNA data (W. J. Baker, unpubl. data, in Asmussen et al. 2006). Henderson and Stevenson (2006), after a analysis of morphological and anatomical features for selected genera, discuss groupings, relationships and character evolution; note that Phoenix and Thrinax are successively sister to the rest of the family...

Additional information may be found in Corner (1966: general, a classic), Tomlinson (1970 - vascular organization in the stem), Uhl and Moore (1971), Moore (1973), Uhl and Dransfield (1987: general, particularly valuable), Zona (1997: general. S.E. U.S.A.), Dransfield and Uhl (1998: general), Harley and Dransfield (2003: pollen), Zona (2004: embryo raphides), Prychid et al. (2004) and Piperno (2006), both SiO₂ bodies/phytoliths, Tomlinson (2006a: general), Bjorholm et al. (2006: patterns of subfamilial diversity in neotropical subfamilies, the Antilles excluded), Henderson (2006: very detailed descriptions of germination, not integrated with phylogeny), Gunawardena and Dengler (2006: leaf development), Sannier et al. (2007: microsporogenesis evolution, Ceroxyloideae not included), and Svenning et al. (200*: diversity of palms in New World). Dransfield et al. (2005) present the outline classification followed here, but with many more details, and Govaerts and Dransfield (2005) a checklist, for which, see also the World Checklist of Monocots.