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, apex multicellular, xylem exarch, branching endogenous; arbuscular mycorrhizae +; shoot apical meristem multicellular; 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 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 via tyrosine pathway [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 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, pollen germinating in less than 3 hours, tube elongated, growing at 80-600 µm/hour, with callose plugs and callose-based walls, penetrating between cells, siphonogamy, penetration of ovules within ca 18 hours, distance to first ovule 1.1.-2.1 mm, 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, 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, stigma ± decurrent, dry [not 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, 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.

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, 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.

NYMPHAEALES [AUSTROBAILEYALES [[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]]]]: vessels +, elements with scalariform perforation plates; ?genome duplication; "DEAER" motif in AP3 and PI genes lost, gaps in these genes.

ROSIDS ET AL. + ASTERIDS ET AL.: root apical meristem closed; (cyanogenesis also via [iso]leucine, valine and phenylalanine pathways); flowers rather stereotyped: 5-merous, parts whorled, calyx and corolla distinct, stamens = 2x K/C, in two whorls developing internally/adaxially to the corolla whorl and successively alternating, (numerous, but then often fasciculate and/or centrifugal), pollen tricolporate, [G 5], [3] also common, compitum +, placentation axile, style +, stigma not decurrent; endosperm nuclear; fruit dry, dehiscent, loculicidal [when a capsule]; euAP1 + euFUL + AGL79 genes [duplication of AP1/FUL or FUL-like gene], PLE + euAG [duplication of AG-like gene: C class], SEP1 + FBP6 genes [duplication of AGL2/3/4 gene].  Back to Main Tree

ASTERIDS ET AL., = SANTALALES [BERBERIDOPSIDALES [CARYOPHYLLALES + ASTERIDS]]: ?

BERBERIDOPSIDALES [CARYOPHYLLALES + ASTERIDS]: ?

BERBERIDOPSIDALES Doweld   Main Tree, Synapomorphies.

Tension wood?; crystals +; petiole bundle annular; stomata cyclocytic; filaments stout; style +; seed endotestal; endosperm development?, embryo? - 2 families, 3 genera, 4 species.

Evolution. it has been suggested that the floral development of Berberidopsis corallina is a "link" in the evolution of the flower of core eudicots (Ronse De Craene 2004, 2007). However, given the phylogenetic position of Berberidopsidaceae and Berberidopsidales, the link is at best a parallelism, or even a connection in the reverse direction; Aextoxicon has tetracyclic (or perhaps pentcyclic) flowers.

Chemistry, Morphology, etc. Carlquist (2003b) details the extensive if largely plesiomorphic similarities in the wood of the two families. Possible synapomorphies, however, include the strong differences between the procumbent cells of the multiseriate parts of the rays and the square to upright cells in the uniseriate portions and also the dark-staining deposits in axial parenchyma and rays. Other details of the vegetative anatomy show (apomorphic?) similarities between the two. Aextoxicon has few druses but numerous rhombic crystals presumably of calcium oxalate; Baas (1984) reported crystals in the leaves of all three genera of Berberidopsidaceae, although druses seem to be commonest. For stomatal morphology, see also P. Soltis and D. Soltis (2004).

Phylogeny. There is good support for this clade in a three-gene tree (e.g. D. Soltis et al. 1999).

Includes Aextoxicaceae, Berberidopsidaceae.

Synonymy: Berberidopsidanae Thorne & Reveal

AEXTOXICACEAE Engler & Gilg, nom. cons.   Back to Berberidopsidales

Tree; chemistry?; true tracheids +; sclereids +; pith heterogeneous; indumentum of peltate scales; leaves opposite, conduplicate, entire; plant dioecious; inflorescence a raceme, (in threes, branching from basal prophylls); flowers (4) 5 (6)-merous, enveloped by bracteoles, K thin, deciduous, C broadly clawed, reniform nectary glands alternating with A; staminate flowers: stamens = and opposite sepals, filaments relatively stout, G vestigial; carpellate flowers: staminodia +, G [2], arrangement?, one locule empty, 2 pendulous apotropous ovules/carpel, micropyle endostomal, inner integument 5-7 layers across, nucellus strongly beaked, style ab?axially curved, apically bilobed; fruit a dry drupe, 1-seeded; seeds carunculate, ruminate, coat tanniniferous, ca 6 cells thick, cell walls thin; endosperm +, ?development, embryo long, curved, ± transverse, cotyledons flattened, cordate-orbicular; n = 16.

1[list]/1: Aextoxicon punctatum. C. Chile (Map: from Donoso Z. 1994). [Photos - Flower, Flower, Flower, Flower, Fruit, Habit]

• Aextoxicaceae are dioecious evergreen trees that can be recognised by their opposite, entire exstipulate leaves that are covered with peltate scales and by their pendulous, racemose inflorescence. The petioles are almost pulvinate at the apex and the base and the lamina appears to be minutely peltate. The flower buds are covered by bracteoles and when they fall off, the almost scale-like sepals fall off with them.

Chemistry, Morphology, etc. Sclereids are found in all vegetative parts of the plant; those of the leaf blade are about half the thickness of the blade in length. The stomata are weakly actinocylic, with 5-7 subsidiary cells. The pith is notably heterogeneous. Although the stigma is bilobed, the bicarpellary construction of the gynoecium should be confirmed. The endocarp appears to split particularly readily along two vertical lines. The embryo is more or less transverse to the long axis of the seed.

For some anatomy, see Pax and Hoffmann (1917), for ovule morphology, see Mauritzon (1936), and for a general account, see Kubitzki (2006b). For fruit and stem anatomy, see Gentry et al. 53436, for leaf anatomy, see Solomon & Solomon 4420.

Previous relationships. Aextoxicaceae have been included in a very heterogeneous Celastrales (Cronquist 1981), placed in Euphorbiales (Takhtajan 1997), and have also been linked with Saxifragales (Qiu et al. 1998).

BERBERIDOPSIDACEAE Takhtajan   Back to Berberidopsidales

Evergreen woody scramblers; isoleucine-derived cyanogenic glycosides +, ellagic acid 0; cork?; fibers non-septate, pits bordered; wood parenchyma vasicentric or apotracheal; (stomata bicyclic); leaves spiral, involute [Berberidopsis], 2ndry veins palmate, margins spiny-toothed or entire; inflorescences terminal; P (9-)12(-15), spiral, all except the outer petaloid, or calyx and corolla distinct, disc lobed, nectariferous, A 6-many, whorled or irregular, filaments short, anthers inserted along connective, connective with apical prolongation, pollen also tricolpate, G [3, 5], placentation parietal, 2-many epi- or pleurotropous ovules/carpel, micropyle bistomal, integuments ca 4 cells across, style stout, stigma punctate to slightly lobed; fruit a berry, K deciduous (persistent - Streptothamnus); (seed with chalazal arilloid - Streptothamnus), exotesta enlarged, fleshy, (inner mesotestal cells sclereids), endotestal cells crystalliferous, palisade, lignified, (exotegmen weakly developed, fibrous, lignified), endotegmen subpersistent; endosperm copious, ?development, embryo short; n = ?21.

2/3. Chile, E. Australia (Map: from Veldkamp 1984). [Photo - Habit, Flower/Fruit.]

• Berberidopsidaceae are woody scramblers that can be recognised by their exstipulate, sometimes spiny-toothed leaf blades with palmate venation; the veins run straight into the spines, when present. The fruit is a berry crowned by the persistent style base.

Chemistry, Morphology, etc. Leaves of Berberidopsis are weakly involute in bud and are not at all imbricated. In Streptothamnus the disc is absent, or perhaps it is to be found between the stamens and the gynoecium.

Some information is taken from Miller (1975: anatomy), van Heel (1979, 1984: seed, pollen), Baas (1984: anatomy), Jaroszewski et al. (1998: cyanogenic glycosides), Takhtajan (1992: seed), and Kubitzki (2006b: general).

Previous Relationships. Berberidopsidaceae were included in Flacourtiaceae by Cronquist (1981) and in Violales by Takhtajan (1997).