EXTANT SEED PLANTS

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 rich in guaiacyl units; true roots present, apex multicellular, xylem exarch, branching endogenous; arbuscular mycorrhizae +; shoot apical meristem multicellular, interface specific plasmodesmatal network; stem with ectophloic eustele, endodermis 0, xylem endarch, branching exogenous; 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 ?; stomata ?; leaf vascular bundles collateral; leaves megaphyllous [determinancy evolved first, then ad/abaxial symmetry], spiral, simple, axillary buds +[?], prophylls [including bracteoles] two, lateral, veins -5 mm/mm² [mean for all non-angiosperms 1.8]; plant heterosporous, sporangia eusporangiate, on sporophylls, sporophylls aggregated in indeterminate cones/strobili; true pollen [microspores, i.e. no distal pore for release of gametes] +, grains mono[ana]sulcate, exine and intine homogeneous; ovules unitegmic, crassinucellate, 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, with cell walls, with many flagellae; 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 [N/O//A/C and P//BE lines], 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 in ANITA grade?], 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 a sieve plate and cytoplasm with P-proteins, companion cells from same mother cell that gave rise to the sieve tube; nodes unilacunar [1:?]; stomata with ends of guard cells level with pore, paracytic, outer stomatal ledges producing vestibule; leaves with petiole and lamina [the latter formed from the primordial leaf apex], development of venation acropetal, 2ndary veins pinnate, fine venation reticulate, veins (1.7-)4.1(-5.7) mm/mm², endings free; flowers perfect, polysymmetric, parts spiral [esp. the A], free, development in general centripetal, numbers unstable; P not sharply differentiated, outer members not enclosing the rest of the bud, smaller than inner members; A many, 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, walls developing by centripetal furrowing; pollen subspherical, binucleate at dispersal, trinucleate eventually, tectum continuous or microperforate, ektexine columellar, endexine thin, compact, lamellate only in the apertural regions; nectary 0; G free, several, ascidiate, with postgenital occlusion by secretion, few [?1] ovules/carpel, ovules marginal, anatropous, bitegmic, [outer integument often largely subdermal in origin, inner integument dermal], micropyle endostomal, integuments 2-3 cells thick, nucellus at apex of ovule 1-3 cells thick, megasporocyte single, megaspore lacking sporopollenin and cuticle, chalazal, female gametophyte four-celled [one-modular, nucleus of egg cell sister to one of the polar nuclei], stylulus short, hollow, cavity not lined by distinct epidermal layer, stigma ± decurrent, dry [not secretory]; P deciduous in fruit; seed exotestal; pollen germinating in less than 3 hours, siphonogamy, tube elongated, growing at 80-600 µm/hour, with callose plugs and callose-based walls, penetrating between cells, penetration of ovules within ca 18 hours, distance to first ovule 1.1.-2.1 mm; tube moves between nucellar cells, 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, minute; 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 + C/PHYB + E gene pairs.

Evolution. Possible apomorphies for flowering plants 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, there is considerable variation between families in particular for several of these characters, and also because details of relationships among gymnosperms will affect the level at which some of these characters are pegged. For example, if reticulate-perforate pollen is optimized to the next node on the tree (see Friis et al. 2009 for a discussion), it effectively makes the pollen morphology of the common ancestor of all angiosperms ambiguous... For other features such a a nucellus only one (Nymphaeales) to three cells thick above the embryo sac and a stylar canal lacking an epidermal layer, although plesiomorphous for basal grade angiosperms (Williams 2009), where on the tree a thicker nucellus and a stylar epidermal layer are acquired has not yet been indicated.

NYMPHAEALES [AUSTROBAILEYALES [[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]]]]: vessels + [one position], elements with elongated scalariform perforation plates; axial parenchyma diffuse or diffuse-in-aggregate; tectum reticulate-perforate [here?]; ?genome duplication; "DEAER" motif in AP3 and PI genes lost, gaps in these genes.

AUSTROBAILEYALES [[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]] : ethereal oils in spherical idioblasts [lamina and P ± pellucid-punctate]; tension wood 0; tectum reticulate-perforate [here?], nucellar cap + [character lost where in eudicots?]; 12BP [4 amino acids] deletion in P1 gene; PHYE +.   Back to Main Tree

Evolution. Soltis et al. (2008: a variety of estimates) date the age of divergence of Austrobaileyales from other angiosperms as some 174-127 million years ago and Moore et al. (2010: 95% highest posterior density) ages of (151-)144(-138) million years; Magallón and Castillo (2009) offer very different ages - ca 235.5 and 129.7 million years for relaxed and constrained penalized likelihood datings respectively.

Chemistry, Morphology, etc. Note that the sampling for the presence/absence of tension wood is poor - only one member of this order is mentioned in Höster and Liese (1966)! For the 12BP deletion, see S. Kim et al. (2003, 2004b) and Aoki et al. (2004).

AUSTROBAILEYALES Reveal  Main Tree, Synapomorphies.

Tiglic acid +; vessels solitary; nodes 1:2; petiole bundle(s) arcuate; leaf margin?; mucilaginous extragynoecial compitum +, outer integument 5-7 cells thick; fruit a berrylet; P deciduous; mesotestal cells ± sclerotic; endosperm starchy [development unknown, 2/4]. - 3 families, 5 genera, 100 species.

Evolution. Magallón and Castillo (2009, which consult for more details) suggest ca 203 million years for relaxed and 125 million years for constrained penalized likelihood crown group datings - probably underestimates.

Pollen tubes grow through mucilage on the style, etc., and reach carpels other than that on which they initially landed (e.g. Williams et al. 1993; Lyew et al. 2007), the distinctive "mucilaginous extragynoecial compitum" of the characterisation above.

Chemistry, Morphology, etc. The wood has paratracheal parenchyma (Carlquist & Schneider 2001). Laterocytic stomata are common in the order, and the cuticle surface is radiate-striate around secretory cells that are to be found on the lower surface of the leaf blade in Austrobaileyaceae and Schisandraceae, at least (see Baranova 2004b for discussion; Carpenter 2006). For embryo sac endosperm development, see Floyd and Friedman (2001), Friedman et al. (2003), Williams and Friedman (2004) and Tobe et al. (2007).

For vegetative anatomy, see Metcalfe (1987), for developmental morphology of ovules and seeds see Yamada et al. (2003a). See Hegnauer (1990) for a discussion of the chemistry of the Polycarpicae, which also includes the magnoliids and Ranunculales.

Phylogeny. For the circumscription of the order, see Soltis et al. (1997) and Källersjö et al. (1999); Trimeniaceae are also to be included (e.g. Qiu et al. 1999). Austrobaileyaceae are sister to the other members of the order.

Includes Austrobaileyaceae, Schisandraceae, Trimeniaceae.

Synonymy: Illicineae J. Presl - Illiciales Cronquist, Schisandrales Blume, Trimeniales Doweld - Trimenianae Doweld - Illiciidae C. Y. Wu

AUSTROBAILEYACEAE Croizat, nom. cons.   Back to Austrobaileyales

Liane; alkaloids 0, flavonols?; primary stem with separate bundles; wood with broad rays; sieve elements with non-dispersive protein bodies; (stomata anomocytic); leaves ± opposite, conduplicate, entire, petiole short; flowers axillary, large, cortical vascular system?; P 12-24; A 6-11, laminar, anthers embedded in connective, 6 or more internal staminodes; G (4-)6-9(-14), (4-)6-8(-14) apotropous ovules/carpel, stigma bilobed at apex; seed ruminate, perichalazal, testa multiplicative, vascularised, sarcotesta +, outer mesotesta lignified; endosperm ?development; n = 22, ?23; germination epigeal.

1[list]/2. Australia (map: from Heywood 1978). [Photo - Flower]

• Austrobaileyaceae are lianes with opposite and entire leaves and large, pendulous flowers. These have spreading petals, many stamens with broad filaments, and internal staminodes. The fruit consists of more or less ellipsoid berrylets.

Chemistry, Morphology, etc. There is some discussion as to whether the highly inclined end walls of the sieve tube have sieve plates, or not (Evert 2006: 393 for literature); in any event, other details of the sieve connections are typically angiosperm. The stylar canal is filled with secretion.

See Endress (1980, 1984) for floral morphology, Carlquist (2001) for wood anatomy; some other information is taken from Endress (1993).

Schisandraceae + Trimeniaceae: stigma dry.

SCHISANDRACEAE Blume, nom. cons.   Back to Austrobaileyales

Tetracyclic triterpenes [cycloartanes], flavonols +, flavones 0, tanniniferous; primary stem ± with vascular cylinder; true tracheids +, astrosclereids +; mucilage cells +; (leaf epidermis silicified); leaves supervolute; A 4-many, latrorse to introrse, pollen tricolpate, syncolpate pole distal, semitectate-reticulate, muri tall, pollen tube growing over epidermis, extragynoecial compitum +; exotesta ± palisade; n = 13, 14.

3/92. Sri Lanka and South East Asia to W. Malesia, S.E. U.S.A., E. Mexico, Greater Antilles.

Illicium L   Back to Austrobaileyales

Shrubs or trees; plants Al accumulators; (pits vestured); nodes 1:1; branching on previous innovation; leaves entire; flowers moderate-sized; P (7-)12-many; G (5-)7-15(-21), pseudo-whorled around axis, occlusion also by postgenital fusion, 1 near basal ovule/carpel, archesporium ³2-celled, stigma dry; fruit a follicle; seed with a circular cap; exotesta with sinuous outer anticlinal walls; endosperm oily.

1/42. South East Asia to W. Malesia, S.E. U.S.A., E. Mexico, Greater Antilles (map: from Wood 1972). [Photo - Flower, Fruit.]

Synonymy: Illiciaceae Berchtold & Presl nom. cons.

Schisandra Blume + Kadsura Jussieu

Lianes; distinctive neolignans, myricetin +; vessel elements with simple perforation plates; nodes 1:3; sclereids fiber-like, with crystals in the walls; stomata also modified laterocytic; leaves (two-ranked; involute), teeth with clear persistent swollen cap into which proceed higher order veins as well as secondaries or tertiaries (margins entire); plant monoecious or dioecious, flowers rather small; P 5-15, A ± connate, pollen heteropolar, (6 colpate); G 12-many, 2-5(-11) ovules/carpel; berrylets usu. 2-seeded, receptacle enlarging greatly; exotesta ± palisade, endotesta also lignified; cotyledons convolute; n also = 7.

2[list]/50. Sri Lanka, East Asia to W. Malesia, S.E. U.S.A., Mexico (map: from Saunders 1998, 2000).[Photo - Infructescence]

Synonymy: Kadsuraceae Radogizky

• Illicium is distinctive with its entire, peppery-tasting leaves borne rather close together at the end of each innovation, but it is its flowers, with several to many perianth parts and the carpels arranged in a single whorl, that are most distinctive. The fruits are follicles each containing a single, shiny seed which is ejected explosively.

Evolution. Illicium, Schisandra glabra (Schisandra s. str.) and Kadsura longipedunculata all have thermogenic flowers (Seymour 2001; Liu et al. 2006; Yuan et al. 2008); pollen may be a floral reward for the pollinator, and/or deceit may be involved. For the growth of the pollen tube over the surface of the epidermis rather than between cells, the presence of an extragynoecial compitum, and the nature of the stigma surface, see Williams et al. (1993) and Lyew et al. (2007).

Chemistry, Morphology, etc. The prophylls of Schizandra are reported to be adaxial (Keller 1996); those I have seen are lateral. The anther connective is especially well developed. The micropyle is endostomal (Yamada et al. 2003).

The vessel member endings of Illicium may also be reticulate. The pollen is modified monosulcate (via trichotomonosulcate). Is the endosperm ever nuclear here? The endotegmen may persist (Corner 1977).

Some general information is taken from Keng (1993), and Saunders (1997, 2000), Sy et al. (1997) discuss phytochemical relationships, while Friedman et al. (2003a, esp. b) and Friedman and Williams (2004) provide information on the female gametophyte; for wood anatomy, see Yang and Lin (2007).

Phylogeny. Kadsura may be paraphyletic, based on the analysis of both trnL-F and ITS sequences, although this is not confirmed by morphological studies (Hao et al. 2001; Denk & Oh 2006; Liu et al. 2006). Liu et al. (2006) discuss character evolution in this group. Molecular and morphological studies also suggest rather different relationships within Illicium (Hao et al. 2000; Oh et al. 2003).

Classification. There is the option in A.P.G. II (2003) of placing the two parts of this quite well characterised clade in separate families, but combination seems in order (A.P.G. III 2009).

TRIMENIACEAE Gibbs, nom. cons.   Back to Austrobaileyales

Trees or lianes; 5-O-methyl flavonols, flavones +, alkaloids?; primary stem with separate bundles; (vessels in radial multiples); rays 6-9-seriate; (secondary phloem with broad rays); mucilage cells +; leaves opposite, margins entire or toothed; inflorescence axillary (terminal), plants monoecious or flowers perfect; flowers small, receptacle small; P 2-many, outer in pairs; A 6-25, anthers latrorse to extrorse (± introrse), connective somewhat prolonged, microsporogenesis successive [tetrads tetragonal], pollen disulcate, polyporate or inaperturate, monads or tetrads, endexine lamellate; G 1 (2), 1 pendulous ovule/carpel, micropyle bistomal, archesporium multicellular, stigma ± penicillate; seed with a circular cap; testa vascularised, almost all walls thick, outer layers lignified, palisade, (mesotesta not lignified); endosperm development?, also with oil, also perisperm +; n = 9.

1-2[list]/6. New Guinea and S.E. Australia to Fiji (map: from van Balgooy 1975; Philipson 1986).

• Trimeniaceae are trees or lianes with opposite, serrate to entire leaves that often have pellucid glands and widely spreading and quite close secondary veins. The wind-pollinated flowers are small, there is usually only a single carpel with a single ovule, and the fruit is a berrylet.

Evolution. Distinctive trimeniaceous seeds, albeit without the vascularised testa of extant taxa, have been found in Late Albian deposits some 118 million years old in Hokkaido, Japan (Yamada et al. 2008).

For pollination, see Bernhardt et al. (2003); stigmatic self-incompatibility occurs here.

Chemistry, Morphology, etc. Some plants of Trimenia papuana have inaperturate pollen, while some have polyporate pollen (Sampson 2007); the endexine is lamellate. The nucellus elongates after meiosis.

See Endress and Sampson (1983) and Philipson (1993) for more information.