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.

ROSIDS ET AL. + ASTERIDS ET AL. / PENTAPETALAE: root apical meristem closed; (cyanogenesis also via [iso]leucine, valine and phenylalanine pathways); flowers rather stereotyped: 5-merous, parts whorled; calyx and corolla distinct, the calyx enclosing the flower in bud, sepals with three or more traces, petals with a single trace; stamens = 2x K/C, in two whorls developing internally/adaxially to the corolla whorl and successively alternating, (numerous, but then usually fasciculate and/or centrifugal); pollen tricolporate; G [5], G [3] also common, when [G 2], carpels superposed, compitum +, placentation axile, style +, stigma not decurrent; endosperm nuclear; fruit dry, dehiscent, loculicidal [when a capsule]; whole genome triplication; RNase-based gametophytic incompatibility system present.  Back to Main Tree

[SANTALALES [BERBERIDOPSIDALES [CARYOPHYLLALES + ASTERIDS]]] / ASTERIDS ET AL. / SUPERASTERIDS : ?

BERBERIDOPSIDALES [CARYOPHYLLALES + ASTERIDS]: ?

Evolution. Divergence & Distribution. Magallón and Castillo (2009) offer estimates of ca 112.5 and 113.1 million years for relaxed and constrained penalized likelihood ages respectively for the divergence of Berberidopsidales from the rest of the clade - but note that the positions of Berberidopsidales and Santalales are switched on their tree - and crown group ages of ca 88.6 and 88.9 million years (relaxed and constrained again). Moore et al. (2010: 95% highest posterior density) suggest ages of (104-)101(-96) million years for stem Berberidopsidales.

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. Magallón and Castillo (2009) offer estimates of ca 112.5 and 113.1 million years for relaxed and constrained penalized likelihood datings respectively for the divergence of stem Berberidopsidales and ages of 88.7 and 88.9 million years for crown divergence (relaxed and constrained again).

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), and that the floral morphology of Aextoxicon, with features like rather variable numbers of sepals and petals, both of which are spirally arranged, are also consistent with this (Ronse De Craene & Stuppy 2010). However, given the phylogenetic position of Berberidopsidales - Santalales are basal to them in the clade immediately leading to the asterids (Moore et al. 2010) - the significance of such features is unclear to me.

Chemistry, Morphology, etc. Carlquist (2003b) details the extensive if probably 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 has long been good support for this clade (e.g. D. Soltis et al. 1999: three-gene tree).

Includes Aextoxicaceae, Berberidopsidaceae.

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

Tree; chemistry?; true tracheids +; sclereids +; pith heterogeneous; indumentum of peltate scales; leaves opposite, lamina vernation conduplicate, margins entire; plant dioecious; inflorescence a raceme, (in threes, branching from basal prophylls); flowers (4) 5 (6)-merous, enveloped by bracteoles; K spiral, thin, deciduous, C spiral, broadly clawed; nectary glands reniform, alternating with A; staminate flowers: stamens = and opposite sepals, filaments relatively stout; G vestigial; carpellate flowers: staminodia +; G 1, style ab?axially curved, apically bilobed; ovules 2/carpel, pendulous, apotropous, micropyle endostomal, outer integument 2-3 cells across, inner integument 5-7 cells across, nucellus massive, strongly beaked funicle quite long, obturator +; fruit a dry drupe, 1-seeded; seeds carunculate, ruminate; coat tanniniferous, ca 6 cells across, 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, there is only a single carpel; a bicarpellary construction of the gynoecium is uncommon here (Ronse DeCraene & Stuppy 2010 for floral development). 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 were of very uncertain position. They 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, lamina vernation involute [Berberidopsis], 2ndry veins palmate, margins spiny-toothed or entire; inflorescences terminal; P (9-)12(-15), spiral, all except the outer petaloid, or K and C distinct; nectariferous disc +, lobed, (?0); A 6-many, whorled or irregular, filaments short, anthers inserted along connective, connective with apical prolongation; pollen also tricolpate; G [3, 5], placentation parietal, style stout, hollow, stigma punctate to slightly lobed; ovules 2-many/carpel, epi- or pleurotropous, micropyle bi- or endostomal, outer integument ca 4 cells across, inner integument ca 4 cells across; fruit a berry, K deciduous (persistent - Streptothamnus); (seed with chalazal arilloid - Streptothamnus); exotestal cells 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. Van Heel (1977) emphasized that the ovules of Berberidopsis were borne directly on the carpel wall, rather than on placentae as in Salicaceae and Achariaceae. 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) because of their parietal placentation.