EMBRYOPSIDA Pirani & Prado
Gametophyte dominant, independent, multicellular, initially ±globular, not motile, branched; showing gravitropism; acquisition of phenylalanine lysase* [PAL], flavonoid synthesis*, microbial terpene synthase-like genes +, triterpenoids produced by CYP716 enzymes, CYP73 and phenylpropanoid metabolism [development of phenolic network], xyloglucans in primary cell wall, side chains charged; plant poikilohydrous [protoplasm dessication tolerant], ectohydrous [free water outside plant physiologically important]; thalloid, leafy, with single-celled apical meristem, tissues little differentiated, rhizoids +, unicellular; chloroplasts several per cell, pyrenoids 0; glycolate metabolism in leaf peroxisomes [glyoxysomes]; centrioles/centrosomes in vegetative cells 0, microtubules with γ-tubulin along their lengths [?here], interphase microtubules form hoop-like system; metaphase spindle anastral, predictive preprophase band + [with microtubules and F-actin; where new cell wall will form], phragmoplast + [cell wall deposition centrifugal, from around the anaphase spindle], plasmodesmata +; antheridia and archegonia +, jacketed*, surficial; blepharoplast +, centrioles develop de novo, bicentriole pair coaxial, separate at midpoint, centrioles rotate, associated with basal bodies of cilia, multilayered structure + [4 layers: L1, L4, tubules; L2, L3, short vertical lamellae] (0), 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 +*, multicellular, growth 3-dimensional*, cuticle +*, plane of first cell division transverse [with respect to long axis of archegonium/embryo sac], sporangium and upper part of seta developing from epibasal cell [towards the archegonial neck, exoscopic], with at least transient apical cell [?level], initially surrounded by and dependent on gametophyte, placental transfer cells +, in both sporophyte and gametophyte, wall ingrowths develop early; suspensor/foot +, cells at foot tip somewhat haustorial; sporangium +, single, terminal, dehiscence longitudinal; meiosis sporic, monoplastidic, MTOC [MTOC = microtubule organizing centre] associated with plastid, sporocytes 4-lobed, cytokinesis simultaneous, preceding nuclear division, quadripolar microtubule system +; wall development both centripetal and centrifugal, 1000 spores/sporangium, sporopollenin in the spore wall* laid down in association with trilamellar layers [white-line centred lamellae; tripartite lamellae]; plastid transmission maternal; nuclear genome [1C] <1.4 pg, main telomere sequence motif TTTAGGG, KNOX1 and KNOX2 [duplication] and LEAFY genes present, ethylene involved in cell elongation; chloroplast genome with close association between trnLUAA and trnFGAA genes [precursors for starch synthesis], tufA, minD, minE genes moved to nucleus; mitochondrial trnS(gcu) and trnN(guu) 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.
Sporophyte well developed, branched, branching dichotomous, potentially indeterminate; hydroids +; stomata on stem; sporangia several, terminal; spore walls not multilamellate [?here].
II. TRACHEOPHYTA / VASCULAR PLANTS
Sporophyte long lived, cells polyplastidic, photosynthetic red light response, stomata open in response to blue light; plant homoiohydrous [water content of protoplasm relatively stable]; control of leaf hydration passive; plant endohydrous [physiologically important free water inside plant]; PIN[auxin efflux facilitators]-mediated polar auxin transport; (condensed or nonhydrolyzable tannins/proanthocyanidins +); xyloglucans with side chains uncharged [?level], in secondary walls of vascular and mechanical tissue; lignins +; roots +, root hairs and root cap +; stem apex multicellular [several apical initials, no tunica], with cytohistochemical zonation, plasmodesmata formation based on cell lineage; vascular development acropetal, tracheids +, in both protoxylem and metaxylem, G- and S-types; sieve cells + [nucleus degenerating]; endodermis +; stomata numerous, involved in gas exchange; leaves +, vascularized, spirally arranged, blades with mean venation density ca 1.8 mm/mm2 [to 5 mm/mm2], all epidermal cells with chloroplasts; sporangia adaxial, columella 0; tapetum glandular; ?position of transfer cells; MTOCs not associated with plastids, basal body 350-550 nm long, stellate array in transition region initially joining microtubule triplets; archegonia embedded/sunken [only neck protruding]; suspensor +, shoot apex developing away from micropyle/archegonial neck [from hypobasal cell, endoscopic], root lateral with respect to the longitudinal axis of the embryo [plant homorhizic].[MONILOPHYTA + LIGNOPHYTA]
Sporophyte growth ± monopodial, branching spiral; roots endomycorrhizal [with Glomeromycota], lateral roots +, endogenous; G-type tracheids +, with scalariform-bordered pits; leaves with apical/marginal growth, venation development basipetal, growth determinate; sporangium dehiscence by a single longitudinal slit; cells polyplastidic, MTOCs diffuse, perinuclear, migratory; blepharoplasts +, paired, with electron-dense material, centrioles on periphery, male gametes multiciliate; nuclear genome size [1C] = 7.6-10 pg [mode]; chloroplast long single copy ca 30kb inversion [from psbM to ycf2]; mitochondrion with loss of 4 genes, absence of numerous group II introns; LITTLE ZIPPER proteins.
Sporophyte woody; stem branching lateral, meristems axillary; lateral root origin from the pericycle; cork cambium + [producing cork abaxially], vascular cambium bifacial [producing phloem abaxially and xylem adaxially].
Growth of plant bipolar [roots with positive geotropic response]; 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); microbial terpene synthase-like genes 0; primary cell walls rich in xyloglucans and/or glucomannans, 25-30% pectin [Type I walls]; lignin chains started by monolignol dimerization [resinols common], particularly with guaiacyl and p-hydroxyphenyl [G + H] units [sinapyl units uncommon, no Maüle reaction]; root stele diarch to pentarch, xylem and phloem originating on alternating radii, cork cambium deep seated; stem apical meristem complex [with quiescent centre, etc.], plasmodesma density in SAM 1.6-6.2[mean]/μm2 [interface-specific plasmodesmatal network]; eustele +, protoxylem endarch, endodermis 0; 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; leaf vascular bundles amphicribral; guard cells the only epidermal cells with chloroplasts, 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, lamina simple; sporangia borne on sporophylls; spores not dormant; 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, exine alveolar/honeycomb; ovules with parietal tissue [= crassinucellate], megaspore tetrad linear, functional megaspore single, chalazal, sporopollenin 0; gametophyte ± wholly dependent on sporophyte, development initially endosporic [apical cell 0, rhizoids 0, etc.]; 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, suspensor short-minute, embryonic axis straight [shoot and root at opposite ends; plant allorhizic], cotyledons 2; embryo ± dormant; chloroplast ycf2 gene in inverted repeat, trans splicing of five mitochondrial group II introns, rpl6 gene absent; ??whole nuclear genome duplication [ζ - zeta - duplication], 2C genome size (0.71-)1.99(-5.49) pg, two copies of LEAFY gene, PHY gene duplications [three - [BP [A/N + C/O]] - copies], 5.8S and 5S rDNA in separate clusters.
IID. 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 cap meristem closed (open); pith relatively inconspicuous, lateral roots initiated immediately to the side of [when diarch] or opposite 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; 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, not occluding pores of plate, companion cell and sieve tube from same mother cell; ?phloem loading/sugar transport; nodes 1:?; dark reversal Pfr → Pr; protoplasm dessication tolerant [plant poikilohydric]; stomata randomly oriented, brachyparacytic [ends of subsidiary cells level with ends of pore], outer stomatal ledges producing vestibule, reduction in stomatal conductance with 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 free, numbers variable, development centripetal; T +, petal-like, 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], each theca dehiscing longitudinally by a common slit, ± embedded in the filament, walls with at least outer secondary parietal cells dividing, endothecium +, cells elongated at right angles to long axis of anther; tapetal 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, intine in apertural areas thick, orbicules +, pollenkitt +; nectary 0; carpels present, superior, free, several, spiral, ascidiate [postgenital occlusion by secretion], stylulus at most short [shorter than ovary], hollow, cavity not lined by distinct epidermal layer, stigma ± decurrent, carinal, dry; suprastylar 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, nucellar cap?; megasporocyte single, hypodermal, functional megaspore lacking cuticle; female gametophyte lacking chlorophyll, 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 bicellular at dispersal, germinating in less than 3 hours, siphonogamy, pollen tube unbranched, growing towards the ovule, 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 gametophytes tricellular, gametes 2, lacking cell walls, ciliae 0, double fertilization +, ovules aborting unless fertilized; P deciduous in fruit; mature seed much larger than fertilized ovule, small [<5 mm long], dry [no sarcotesta], exotestal; endosperm +, ?diploid, 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, embryo short [<¼ length of seed]; plastid and mitochondrial transmission maternal; Arabidopsis-type telomeres [(TTTAGGG)n]; nuclear genome [2C] (0.57-)1.45(-3.71) [1 pg = 109 base pairs], ??whole nuclear genome duplication [ε/epsilon event]; 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, palaeo AP3 and PI genes [paralogous B-class genes] +, with "DEAER" motif, SEP3/LOFSEP and three copies of the PHY gene, [PHYB [PHYA + PHYC]]; chloroplast chlB, -L, -N, trnP-GGG genes 0.
[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]]]] : phloem loading passive, via symplast, plasmodesmata numerous; vessel elements with scalariform perforation plates in primary xylem; essential oils in specialized cells [lamina and P ± pellucid-punctate]; tension wood + [reaction wood: with gelatinous fibres, G-fibres, on adaxial side of branch/stem junction]; anther wall with outer secondary parietal cell layer dividing; tectum reticulate; nucellar cap + [character lost where in eudicots?]; 12BP [4 amino acids] deletion in P1 gene; PHYE +. Back to Main Tree
Age. Wikström et al. (2001) suggested an age of (172-)165, 147(-140) m.y. for this node, while ages in Bell et al. (2010: BEAST exponential and lognormal respectively) are (187-)173(-160) or (150-)144(-138) m.y.; Soltis et al. (2008) give dates of some 174-127 m.y., Moore et al. (2010) ages of (151-)144(-138) m.y., and Iles et al. (2014) ages of (145.6-)140.2(-135.5) m.y.a, while ca 137.7 m.y.a. is the age in Magallón et al. (2015). Magallón and Castillo (2009) offer very divergent estimates - ca 235.5 and 129.7 m.y. for relaxed and constrained penalized likelihood datings respectively. Foster et al. (2016a: q.v. for details) suggest an age of cs 195 m.y., Clarke et al. (2011: q.v. for other estimates) ages of (208-)177(-152) m.y., N. Zhang et al. (2012; Xue et al. 2012 are very similar) ages of (185-)161(-146) m.y., and Magallón et al. (2013) an age of around 170.4 m.y. ago. At (250, 215-)211, 180(-156), ca 237, and (267-)228(-192) m.y.a., the estimates by Zeng et al. (2014), Z. Wu et al. (2014) and Salomo et al. (2017) respectively are towards the upper end of the spectrum.
A fossil-based estimate for the age of this clade is ca 113 m.y. (Crepet et al. 2004).
Chemistry, Morphology, etc. See Hegnauer (1990) for a discussion of the chemistry of the Polycarpicae, which also includes the magnoliids and Ranunculales. The sampling for the presence/absence of tension wood is poor, for instance, only one member of Austrobaileyales is mentioned in Höster and Liese (1966), and its position at this node is only provisional. However, in a number of taxa that appear to lack a G layer, it becomes lignified, and so its absence is only apparent (Roussel & Clair 2015). Cuticular striations are known to occur only at and above this node (Upchurch 2013).
Columellar infratectal structure of pollen grains may be best optimised here; the plesiomorphic condition is granular, also found in the pollen of 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.
Tiglic acid +; vessels solitary; nodes 1:2; petiole bundle(s) arcuate; lamina margin?; P spiral; A spiral; G spiral; outer integument 5-7 cells thick; fruit a drupelet; P deciduous; mesotestal cells ± sclerotic. - 3 families, 5 genera, 100 species.
Age. Tank et al. (2015: Table S2) thought that this node might be ca 179 m.y.o., Wikström et al. (2001) suggested an age of (155-)148, 133(-126) m.y. for crown Austrobaileyales, Schneider et al. (2004) ages of 168 and 85 m.y., Magallón and Castillo (2009) ages of ca 203 and 125 m.y., Salomo et al. (2017) ages of (166-)131(-106) m.y., Bell et al. (2010) ages of (145-)122(-99) (see also Magallón et al. 2015) or (130-)114(-110) m.y., while Iles et al. (2014) suggested an age of (130.8-)118.3(-109.9) m.y. ago. Somewhat younger estimates include those by Magallón et al. (2013) who thought that this node might be some 103.4 m.y. old, while ca 91.5 m.y. is the estimate in Naumann et al. (2013).
Note: In all node characterizations, boldface denotes possible apomorphies, (....) denotes a feature the exact status of which in the clade is uncertain, [....] includes explanatory material; other text lists features found pretty much throughout the clade. Note that the particular node to which many characters, particularly the more cryptic ones, should be assigned is unclear. This is partly because homoplasy is very common, in addition, basic information for all too many characters 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. Endress and Doyle (2015) discuss some apomorphies (floral morphology).
Ecology & Physiology. For the evolution of the liane habit, common here, in the context of plants with rather unspecialized vascular systems, see Feild and Isnard (2013) and Isnard and Feild (2015).
Pollination Biology & Seed Dispersal. Thien et al. (2009) survey what is known about pollination in the clade.
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 the secretory cells on the lower surface of the leaf blade in Austrobaileyaceae and Schisandraceae, at least (Baranova 2004b for discussion; Carpenter 2006).
For vegetative anatomy, see Metcalfe (1987), for some developmental morphology of ovules and seeds, inc. details of lobing, etc., at micropyle, see Yamada et al. (2003a). For embryo sac and endosperm development, see Floyd and Friedman (2001), Friedman et al. (2003), J. H. Williams and Friedman (2004) and Tobe et al. (2007).
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, climbing by twining; alkaloids 0, flavonols?; primary stem with separate bundles; wood with broad rays; sieve elements with non-dispersive protein bodies; calcium oxalate as crystal sand; (stomata anomocytic); leaves ± opposite, lamina vernation conduplicate, margins entire, petiole short; flowers axillary, large [ca 5 cm across], cortical vascular system?; P 12-24, with two traces; A 6-11, laminar, vascular bundle(s) branching, anthers embedded in connective, staminodes internal, 6-16; G (4-)6-9(-14), stigma bilobed; ovules (4-)6-8(-14)/carpel, apotropous, outer integument to 10 cells across, chalazal end of ovule massive; seeds ruminate, large [>2 cm long]; perichalazal; testa multiplicative, vascularized, sarcotesta +, outer mesotesta lignified; transient starchy perisperm, endosperm starchy; n = 22, ?23; germination epigeal.
1 [list]/2. Australia (map: from Heywood 1978). [Photo - Flower.]
Evolution. Ecology & Physiology. For the ecophysiology of Austrobaileya scandens, a liane that can tolerate shade, see Feild et al. (2003b).
Pollination Biology & Seed Dispersal. For pollination - possibly sapromyophily - see Gottsberger (2016a). The stigmas are postgenitally united by secretion (Losada et al. 2017).
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 angiospermous. The stylar canal is filled with secretion.
See Bailey and Swamy (1949) and Endress (1993) for general information, Carlquist (2001) for wood anatomy, Behnke (1986) for phloem anatomy, pores are very narrow, Endress (1980a, 1984) for floral morphology, Zavada (1984) for pollen (c.f. Furness 2014) and Losada et al. (2017), for seed development and germination - 2 years + all told!
[Schisandraceae + Trimeniaceae]: flowers <3 cm across; pollen other than mono[ana]sulcate; infra-stylar extra-gynoecial compitum/pollen tube growth; stigma dry; megaspore mother cells 2-many; exotesta ± palisade.
Age. Ages for this node of (107.9-)102.1(-98.8.) m.y.a. (Iles et al. 2014), ca 109.7 m.y.a. (Magallón et al. 2015), (116-)106(-101) m.y. (Salomo et al. 2017) or as much as around 158.6 m.y. (Tank et al. 2015: Table S2) have been suggested.
Anacostia, fossils with graded-reticulate monosulcate to trichotomosulcate pollen and exotestal seeds from Cretaceous (Barremian-Aptian) deposits some 130-115 m.y. old of E. North America and Portugal (Friis et al. 1997b), may be sister to Schisandraceae (Doyle & Endress 2010, 2014; Doyle & Upchurch 2014), not really compatible with the estimate in the preceding paragraph. However, Friis et al. (2011) found the fossils hard to place.
SCHISANDRACEAE Blume, nom. cons. Back to Austrobaileyales
Tetracyclic triterpenes [cycloartanes], flavonols +, flavones 0, ellagic acid +; primary stem ± with vascular cylinder; (phoem fibres +); true tracheids +; astrosclereids +; mucilage cells +; (leaf epidermis silicified); lamina vernation supervolute; A 4-many, latrorse to introrse, pollen tricolpate, syncolpate at the poles, semitectate-reticulate, muri tall; stigma dry; extragynoecial compitum +; exotesta with sinuous anticlinal cell walls, ?lignified mesotesta; n = 13, 14.
3 [list]/92 - two groups below. Sri Lanka and South East Asia to W. Malesia, S.E. U.S.A., E. Mexico, Greater Antilles.
Age. Magallón et al. (2013) suggested an age for crown-group Schisandraceae of around 42.2 m.y. and Naumann et al. (2013) an age of ca 40 m.y., and estimates are slightly under 50 m.y. in N. Zhang et al. (2012). Ages in Luo et al. (2018) and Morris et al. (2007) are very different, the ages being around 135.8 m.y. and 131.7 m.y. respectively, while those in Wikström et al. (2001) at (119-)108, 93(-82) m.y. are somewhat intermediate, as are those in Bell et al. (2010), at 91-89 m. years. The first pair of ages in particular are likely to be severe underestimates if the identity of the trimeniaceous fossil seed (see below) is correct.
1. Illicium L.
Shrubs or trees; plants Al accumulators; (pits vestured); nodes 1:1; branching on previous innovation; leaves pseudoverticillate, lamina margins entire; P (7-)12-many; A (7-10); pollen isopolar; G (5-)7-15(-21), pseudo-whorled, basi-laterally connate, residual axis massive; G occlusion also by postgenital fusion; ovule 1/carpel, near basal, parietal tissue ca 6 cells across; fruit an explosive follicle; seed with a circular cap, endocarp palisade, lignified; testa multiplicative; endosperm lacking starch, develops in chalazal half [?level].
1/42. South East Asia to W. Malesia, S.E. U.S.A., E. Mexico, Greater Antilles (map: from Wood 1972). [Photo - Flower, Fruit.]
Age. Morris et al. (2007) suggested that crown group Illicium was (91.5-)89.4, 76.3(-72.2) m.yo., Salomo et al. (2017) suggested an age of (93-)64(-34) m.y., while ca 45.1 m.y. is the age in Luo et al. (2018).
Synonymy: Illiciaceae Berchtold & Presl nom. cons.
2. Schisandra Blume + Kadsura Jussieu
Lianes, climbing by twining; (silicon concentration high); distinctive neolignans, myricetin +; vessel elements with simple perforation plates, (torus-margo pits + - Schisandra); 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; P 5-15; staminate flowers: A (4-7), ± connate, endothecium biseriate; pollen grains heteropolar, not syncolpate at proximal pole, (6 colpate - 3 long, meeting at one pole, 3 short); pistillodes 0; carpellate flowers: staminodes 0; G 12-many, stigma papillate; ovules 2-5(-11)/carpel, parietal tissue 2-4 cells across, nucellar cap ca 2 cells across; (more than one embryo sac developing); fruit berrylets, usu. 2-seeded, inner hypodermal layer of pericarp with anticlinally-elongated cells receptacle enlarging greatly; endotesta also lignified; cotyledons convolute; n also = 7.
2/50. Sri Lanka, East Asia to W. Malesia, S.E. U.S.A., Mexico (map: from Saunders 1998, 2000).[Photo - Infructescence.]
Age. The crown-group age of this clade is ca 66.2 m.y. (Luo et al. 2018).
Synonymy: Kadsuraceae Radogizky
Evolution: Divergence & Distribution. For the fossil record of Schisandraceae, which dates back only to the Late Cretaceous, see Friis et al. (2011).
Z. Liu et al. (2006) discuss character evolution in Schizandra.
Pollination 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; Luo et al. 2010). It has been suggested that pollen may be a floral reward for the pollinator, the pollinator may also oviposit, and/or deceit pollination may be involved (see also Gottsberger 2016a); reports of nectar/nectaries need to be substantiated (Erbar 2014). Details of pollination, with small diptera the commonest pollinators, have recently been clarified (see especially Luo et al. 2010, 2017b, 2018). Luo et al. found that pollination in the whole family was predominantly by nocturnal resin-feeding gall midges, beetle pollination being quite uncommon and a derived condition. In Kadsura midges laid eggs in the flowers, usually in the androecium or gynoecium, but in K. coccinea, sister to the rest of the genus, eggs are laid on inner members of the perianth. Luo et al. (2017b) described how the midge larvae ate resinous substances produced by the plant (the sesquiterpene caryophyllene was a major component) when its tissues were damaged by the midge when it was laying eggs - the larvae ate such floral exudates, but not pollen or ovules. Only female midges visited the flowers, and each species of Kadsura, for example, was visited by a different species of midge. In this midge-Schisandraceae system, larval development can be quite a protracted affair (Luo et al. 2010, 2017b).
Luo et al. (2018) suggested that plant-pollinator relationships here were an example of Jansenian co-evolution: "interacting guilds of plants and arthropods coevolve" (ibid.: p. 7), although without strictly coinciding divergence times being expected. Dates are indeed interesting here. Ignoring error bars, divergence in Schisandraceae, in all three genera of which the midge Resseliella is the major pollinator, began ca 135.8 m.y.a., the midge itself still being a mere idea in the mind of god - divergence in the midges studied began only ca 11.2 m.y.a. (the species in the first-diverging midge clade does not lay its eggs in the flower, but the species of Kadsura it pollinates cannot be thought of as being "primitive" - Luo et al. 2018). Similarly, Luo et al. (2017b) suggest a crown age for Kadsura of about 40 m.y., and for its pollinating Resseliella of ca 11.2 m.y., the ranges not even overlapping. Although hardly co-evolution, Luo et al. (2018) suggest that extinct midges might have been pollinators here - perhaps a not unreasonable suggestion, but hardly satisfying, since they must have been involved for 110 m.y. or so. Luo et al. (2018) also mention the small size of Schisandraceae flowers, interesting, given the small size of many early angiosperm fossil flowers...
For the growth of the pollen tube through mucilage on 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 E. G. Williams et al. (1993), Lyew et al. (2007), Du and Wang (2012), and Luo et al. (2017b) and references; for an infrastylar extragynoecial compitum in Illicium, see X.-F. Wang et al. (2011).
Romanov et al. (2013) discuss the the explosive dehiscence of the follicle of Illicium and its distinctive anatomy.
Chemistry, Morphology, etc. The vessel member endings of Illicium may also be reticulate. The prophylls of Schizandra are reported to be adaxial (Keller 1996); those I have seen are lateral.
In Schisandra, at least, the parts of the perianth that are exposed in bud are sepal-like on their exteriors (Warner et al. 2009). The anther connective is especially well developed. The pollen is modified monosulcate (via tritomosulcate). 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, for wood anatomy, see Yang and Lin (2007), for floral development, see Robertson and Tucker (1979), Tucker (1984), Tucker and Bourland (1994) and Dong et al. (2012), for pollen morphology, see Praglowski (1976) and Wang et al. (2010) and for embryology, etc., see Kapil and Jalan (1964: 4-nucleate embryo sac); Floyd and Friedman (2001) outline endosperm development, while Swamy (1964a: embryo sac unlike any others he knew), Friedman et al. (2003a, esp. b) and Friedman and Williams (2004) provide information on the female gametophyte.
Phylogeny. Kadsura may be paraphyletic, based on the analysis of both trnL-F and ITS sequences, although paraphyly is not found in morphological analyses (Hao et al. 2001; Denk & Oh 2006; Liu et al. 2006). Molecular and morphological studies also suggest rather different relationships within Illicium (Hao et al. 2000; Oh et al. 2003). Within Kadsura s. str., the distinctive K. coccinea, in which the inner perianth members are much swollen, is sister to the rest of the genus (Luo et al. 2017b).
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); (nodes 1:4); mucilage cells +; leaves opposite, lamina margins entire or toothed; inflorescence axillary (terminal), branched; plants monoecious or flowers perfect; receptacle small; P 2-many, outer members in pairs; A 6-25, anthers latrorse to extrorse (± introrse), connective somewhat prolonged; pollen disulcate, pantoporate or inaperturate, monads or tetrads, endexine lamellate; G 1 (2), style 0, stigma ± penicillate; compitum necessarily 0; ovule 1/carpel, pendulous, micropyle bistomal, parietal tissue 9-30+ cells across, nucellar cap ca 6 cells across, hypostase +; megaspore mother cells at base of nucellus, embryo sac much elongated (few), reaching micropyle; seed with a circular cap; testa vascularized, almost all cell walls thick, outer layers lignified, palisade, (mesotesta not lignified); thin layer of nucellus persistent, embryo suspensor multicellular, multiseriate; n = 9.
1 [list]/6. New Guinea and S.E. Australia to Fiji (map: from van Balgooy 1975; Philipson 1986b).
Age. Distinctive trimeniaceous seeds, albeit without the vascularized testa of extant taxa, have been found in Late Albian deposits some 118 m.y.o. in Hokkaido, Japan (Yamada et al. 2008).
Evolution: Pollination Biology & Seed Dispersal. For pollination, see Bernhardt et al. (2003) and Luo et al. (2018); stigmatic self-incompatibility occurs here, and both wind and insects may be involved in pollination.
Chemistry, Morphology, etc. Some plants of Trimenia papuana have inaperturate pollen, while some have polyporate pollen (Sampson 2007); the endexine is lamellate. The nucellus sometimes elongates greatly after meiosis of the megaspore mother cells, but the origin of the cells making up the massive nucellus and through the central, starch-rich cells of which the embryo sac grows (Bachelier & Friedman 2011; Friedman & Bachelier 2013) and of the megaspore mother cells themselves is unclear; are the latter hypodermal when they are first evident? Friedman and Bachelier (2013: much useful information) observed a thin, persistent layer of nucellar tissue surrounding the endosperm in the seed, but it did not contain food reserves.
See also Endress and Sampson (1983: floral development) and Philipson (1986b, 1993) for more information.