LIGNOPHYTA

True roots +; lateral meristems: cork cambium producing cork abaxially, vascular cambium producing phloem abaxially and xylem adaxially.

EXTANT SEED PLANTS/SPERMATOPHYTA

Plant woody, evergreen; nicotinic acid metabolised to trigonelline, (cyanogenesis via tyrosine pathway); primary cell walls rich in xyloglucans and/or glucomannans, 25-30% pectin [Type I walls]; lignins derived from (some) sinapyl and particularly coniferyl alcohols, thus containing p-hydroxyphenyl and guaiacyl lignin units, (lignins derived from p-coumaryl alcohol, i.e. S [syringyl] lignin units); true roots present, apex multicellular, xylem exarch, and 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 and rays alone, tracheid/tracheid pits circular, bordered; mature sieve tube/cell lacking functioning nucleus, plastids with starch grains; phloem fibres +; stem cork cambium superficial, root cork cambium deep seated; leaves with single trace from sympodium ["nodes 1:1"]; stomata ?; leaf vascular bundles collateral; leaves megaphyllous [determinancy evolved first, then ad/abaxial symmetry], spiral, simple, lamina with vein density up to 5 mm/mm2 [mean for all non-angiosperms 1.8]; axillary buds associated with at most some leaves; prophylls [including bracteoles] two, lateral; 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, developing after pollination, 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 duplications [three - [BP [A/N + C/O]] - copies], nrDNA with 5.8S and 5S rDNA in separate clusters; mitochondrial nad1 intron 2 and coxIIi3 intron and trans-spliced introns present.

MAGNOLIOPHYTA

Lignans, O-methyl flavonols, dihydroflavonols, triterpenoid oleanane, non-hydrolysable tannins, quercetin and/or kaempferol +, apigenin and/or luteolin scattered, [cyanogenesis in ANITA grade?], S [syringyl] lignin units common, positive Maüle reaction [syringyl:guaiacyl ratio more than 2-2.5:1], and hemicelluloses as xyloglucans; root apical meristem intermediate-open; root vascular tissue oligarch [di- to pentarch], lateral roots arise opposite or immediately to the side of [when diarch] xylem poles; origin of epidermis with no clear pattern [probably from inner layer of root cap], trichoblasts [differentiated root hair-forming cells] 0; shoot apex with tunica-corpus construction, tunica 2-layered; reaction wood ?, with gelatinous fibres; 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 cells from same mother cell that gave rise to the sieve tube; sugar transport in phloem passive; nodes unilacunar [1:?]; stomata with ends of guard cells level with pore, paracytic, outer stomatal ledges producing vestibule; leaves petiolate, lamina [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; most/all leaves with axillary buds; flowers perfect, pedicellate, polysymmetric, parts spiral [esp. the A], free, numbers unstable, development in general centripetal; P not sharply differentiated, with a single trace, outer members not enclosing the rest of the bud, often smaller than inner members; A many, filament not sharply distinguished from anther, stout, broad, with a single trace, anther introrse, tetrasporangiate, sporangia in two groups of two [dithecal], ± embedded in the filament, with at least outer secondary parietal cells dividing, each theca dehiscing longitudinally 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, 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, stylulus short, hollow, cavity not lined by distinct epidermal layer, stigma ± decurrent, dry [not secretory]; ovules few [?1]/carpel, marginal, anatropous, bitegmic, micropyle endostomal, outer integument 2-3 cells across, often largely subdermal in origin, inner integument 2-3 cells across, often dermal in origin, parietal tissue 1-3 cells across [crassinucellate], nucellar cap?; megasporocyte single, hypodermal, megaspore tetrad linear, functional megaspore chalazal, lacking sporopollenin and cuticle; female gametophyte four-celled [one module, nucleus of egg cell sister to one of the polar nuclei]; P deciduous in fruit; seed exotestal; pollen binucleate at dispersal, trinucleate eventually, germinating in less than 3 hours, pollination siphonogamous, tube elongated, growing at 80-600 µm/hour, with pectic outer wall, callose inner wall and callose plugs, growing between cells, penetration of ovules via micropyle [porogamous] within ca 18 hours, distance to first ovule 1.1.-2.1 mm, tube moves between nucellar cells; double fertilisation +, endosperm diploid, cellular [micropylar and chalazal domains develop diffently, 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, embryo cellular ab initio, minute; germination hypogeal, seedlings/young plants sympodial; Arabidopsis-type telomeres [(TTTAGGG)n]; whole genome duplication, ndhB gene 21 codons enlarged at the 5' end, single copy of LEAFY and RPB2 gene, knox genes extensively duplicated [A1-A4], AP1/FUL gene, paleo AP3 and PI genes [paralogous B-class genes] +, with "DEAER" motif, SEP3/LOFSEP and three copies of the PHY gene, [PHYB [PHYA + PHYC]].

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. This is because some taxa basal to the [magnoliid + monocot + eudicot] group have been surprisingly little studied, there is considerable homoplasy as well as variation within and between families of the ANITA grade 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 as details of sugar transport in the phloem, their placement on the tree is frankly speculative. Finally, for features such as parietal tissue/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), I am unsure where on the tree a thicker nucellus and a stylar epidermal layer are acquired.

NYMPHAEALES [AUSTROBAILEYALES [[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]]]]: vessels +, elements with elongated scalariform perforation plates; wood fibres +; axial parenchyma diffuse or diffuse-in-aggregates; 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. Divergence & Distribution. Bell et al. (2010) suggest ages for this clade of (187-)173(-160) or (150-)144(-138) million years depending on the method used. 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 divergent estimates - ca 235.5 and 129.7 million years for relaxed and constrained penalized likelihood datings respectively. A fossil-based estimate is a mere ca 113 million years (Crepet et al. 2004), while Davies et al. (2011: 95% credibility intervals) again suggested an older age of (208-)177(-152) million years.

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)! Columellar infratectal strucutre may be best optimised here; the plesiomorphic condition is granular, the same infrastructure also being found in several Magnoliales, Monimiaceae, etc., as reversals (Doyle et al. 1990b). 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; lamina margin?; mucilaginous extragynoecial compitum +, outer integument 5-7 cells thick; fruit a berrylet; P deciduous; mesotestal cells ± sclerotic; endosperm starchy [development unknown, 2/3]. - 3 families, 5 genera, 100 species.

Evolution. Divergence & Distribution. 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.

Floral Biology & Seed Dispersal. 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 Martius, Trimeniales Doweld - Schisandrineae Shipunov - Austrobaileyanae Chase & Reveal, Illicianae 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, lamina vernation conduplicate, margins 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), stigma bilobed at apex; ovules (4-)6-8(-14)/carpel, apotropous; seeds ruminate, perichalazal, testa multiplicative, vascularized, sarcotesta +, outer mesotesta lignified; endosperm ?development; n = 22, ?23; germination epigeal.

Austrobaileyaceae

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

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 Bailey and Swamy (1949) for general morphology and anatomy, Behnke (1986: phloem anatomy, pores very narrow), Endress (1980a, 1984) for floral morphology, Carlquist (2001) for wood anatomy; some other information is taken from Endress (1993).

Schisandraceae + Trimeniaceae: pollen other than mono[ana]sulcate; stigma dry; megaspore mother cells 2-many.

Evolution. Divergence & Distribution. Doyle and Endress (2010) suggest that Anacostia, a fossil with graded-reticulate monosulcate to trichotomosulcate pollen and exotestal seeds from Cretaceous (Barremian-Aptian) deposits some 130-115 million years old of East North America and Portugal (Friis et al. 1997b), might be sister to Schisandraceae.

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); lamina vernation 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.   

Shrubs or trees; plants Al accumulators; (pits vestured); nodes 1:1; branching on previous innovation; lamina margins entire; flowers moderate-sized; P (7-)12-many; G (5-)7-15(-21), pseudo-whorled around axis, occlusion also by postgenital fusion, stigma dry; ovule 1/carpel, near basal, micropyle exostomal, outer integument 3-4 cells across; fruit a follicle; seed with a circular cap; testa multiplicative, exotesta with sinuous outer anticlinal walls; endosperm oily.

<i>Illicium</i>

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; (silicon concentration high); distinctive neolignans, myricetin +; vessel elements with simple perforation plates; nodes 1:3; sclereids fibre-like, with crystals in the walls; stomata also laterocytic; leaves (two-ranked), Lamina (vernation 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, stigma dry [Kadsura longipedicellata], papillate; ovules 2-5(-11)/carpel, outer integument 5-7 cells across, parietal tissue 2-3 cells across, nucellar cap ca 2 cells across; (more than one embryo sac developing); berrylets usu. 2-seeded, receptacle enlarging greatly; exotesta ± palisade, endotesta also lignified; cotyledons convolute; n also = 7.

<i>Schisandra</i>, etc.

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

Evolution. Floral Biology & Seed Dispersal. 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, i.e. 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). The endotegmen may persist (Corner 1977).

Some general information is taken from Bailey and Nast (1948), Keng (1993), and Saunders (1997, 2000), Sy et al. (1997) discuss phytochemical relationships, Floyd and Friedman (2001) outline endosperm development, while Swamy (1964a: he noted that the embryo sac was unlike any others he knew), 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) and for pollen morphology, see Wang et al. (2010).

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, lamina margins entire or toothed; inflorescence axillary (terminal), plants monoecious or flowers perfect; flowers small, receptacle small; P 2-many, outer in pairs, otherwise spiral; 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), stigma ± penicillate; ovule 1/carpel, pendulous, micropyle bistomal, parietal tissue ca 9 cells across, nucellar cap ca 6 cells across, hypostase +; megaspore mother cells at base of nucellus, embryo sacs 1-few, much elongated, reaching micropyle; seed with a circular cap; testa vascularized, almost all walls thick, outer layers lignified, palisade, (mesotesta not lignified); endosperm development?, also with oil, also perisperm +; n = 9.

Trimeniaceae

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

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

Floral Biology & Seed Dispersal. 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 greatly after meiosis of the megaspore mother cells, but the origin of the cells making up the massive nucellus (all told, 20+ cells across - Bachelier ± Friedman 2011) and of the megaspore mother cells themselves is unclear; are the latter initially hypodermal?

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