EMBRYOPSIDA Pirani & Prado

Gametophyte dominant, independent, multicellular, thalloid, with single-celled apical meristem, showing gravitropism; rhizoids +, unicellular; flavonoids + [absorbtion of UV radiation]; chloroplasts lacking pyrenoids; protoplasm dessication tolerant [plant poikilohydric]; cuticle +; cell walls with (1->4)-ß-D-glucans [xyloglucans], lignin +; several chloroplasts per cell; glycolate metabolism in leaf peroxisomes [glyoxysomes]; centrioles in vegetative cells 0, metaphase spindle anastral, predictive preprophase band of microtubules, phragmoplast + [cell wall deposition spreading from around the spindle fibres], plasmodesmata +; antheridia and archegonia jacketed, stalked; spermatogenous cells monoplastidic, centrioles develop de novo, associated with basal bodies of flagellae, multilayered structure +, proximal end of basal bodies lacking symmetry, stellate pattern associated with doublet tubules of transition zone; spermatozoids with a left-handed coil; male gametes with 2 lateral flagellae; oogamy; diploid embryo initially surrounded by haploid gametophytic tissue, plane of first division horizontal [with respect to long axis of archegonium/embryo sac], suspensor/foot +, cell walls with nacreous thickenings; sporophyte multicellular, with at least transient apical cell [?level], sporangium +, single, dehiscence longitudinal; meiosis sporic, monoplastidic, microtubule organizing centre associated with plastid, cytokinesis simultaneous, preceding nuclear division, sporocytes 4-lobed, with a quadripolar microtubule system; spores in tetrads, sporopollenin in the spore wall, wall with several trilamellar layers [white-line centred layers, i.e. walls multilamellate]; close association between the trnLUAA and trnFGAA genes on the chloroplast genome.

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 common ancestor of the group.

STOMATOPHYTES

Abscisic acid, ?D-methionine +; sporangium with seta, seta developing from basal meristem [between epibasal and hypobasal cells], sporangial columella + [developing from endothecial cells]; stomata +, anomocytic, cell lineage that produces them with symmetric divisions [perigenous]; underlying similarities in the development of conducting tissue and in rhizoids/root hairs; spores trilete; polar transport of auxins and class 1 KNOX genes expressed in the sporangium alone; MIKC, MI*K*C* and class 1 and 2 KNOX genes, post-transcriptional editing of chloroplast genes; gain of three group II mitochondrial introns.

[Anthocerophyta + Polysporangiophyta]: archegonia embedded/sunken in the gametophyte; sporophyte long-lived, chlorophyllous, nutritionally largely independent of the gametophyte; sporophyte-gametophyte junction interdigitate, sporophyte cells showing rhizoid-like behaviour.

POLYSPORANGIOPHYTA†

Sporophyte well developed, branched, free living, sporangia several; spore walls not multilamellate [?here]; apical meristem +.

EXTANT TRACHEOPHYTA / VASCULAR PLANTS

Photosynthetic red light response; water content of protoplasm relatively stable [plant homoiohydric]; control of leaf hydration passive; (condensed or nonhydrolyzable tannins/proanthocyanidins +); sporophyte with basipetal polar auxin transport; vascular tissue +, sieve cells + [nucleus degenerating], tracheids +, in both protoxylem and metaxylem; endodermis +; root xylem exarch [development centripetal]; stem with an apical cell; branching dichotomous; leaves spirally arranged, blades with mean venation density 1.8 mm/mm2 [to 5 mm/mm2]; sporangia adaxial on the sporophyll, derived from periclinal divisions of several epidermal cells, wall multilayered [eusporangium]; columella 0; tapetum glandular; gametophytes exosporic, green, photosynthetic; stellate pattern split between doublet and triplet regions of transition zone; placenta with single layer of transfer cells in both sporophytic and gametophytic generations, embryonic axis not straight [root lateral with respect to the longitudinal axis; plant homorhizic].

[MONILOPHYTA + LIGNOPHYTA]

Branching ± monopodial; lateral roots +, endogenous, root apex multicellular, root cap +; tracheids with scalariform-bordered pits; leaves with apical/marginal growth, venation development basipetal, growth determinate; sporangia borne in pairs and grouped in terminal trusses, dehiscence longitudinal, a single slit; cells polyplastidic, microtubule organizing centres not associated with plastids, diffuse, perinuclear; male gametes multiflagellate, basal bodies staggered, blepharoplasts paired; chloroplast long single copy ca 30kb inversion [from psbM to ycf2].

LIGNOPHYTA†

Plant woody; lateral root origin from the pericycle; branching lateral, meristems axillary; cork cambium + [producing cork abaxially], vascular cambium bifacial [producing phloem abaxially and xylem adaxially].

EXTANT SEED PLANTS / SPERMATOPHYTA

Plant 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 [hence with p-hydroxyphenyl and guaiacyl lignin units, so no Maüle reaction]; root stele with xylem and phloem originating on alternate radii, not medullated [no pith], cork cambium deep seated; arbuscular mycorrhizae +; shoot apical meristem interface specific plasmodesmatal network; stem with vascular cylinder around central pith [eustele], phloem abaxial [ectophloic], endodermis 0, xylem endarch [development centrifugal]; 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 +; stem cork cambium superficial; branches exogenous; leaves with single trace from vascular sympodium [nodes 1:1]; stomatal pore with active opening in response to leaf hydration, control by abscisic acid, metabolic regulation of water use efficiency, etc.; leaves with petiole and lamina, development basipetal, blade simple; axillary buds +, (not associated with all leaves); prophylls two, lateral; plant heterosporous, sporangia borne on sporophylls; microsporophylls aggregated in indeterminate cones/strobili; true pollen +, grains mono[ana]sulcate, exine and intine homogeneous; ovules unitegmic, parietal tissue 2+ cells across, megaspore tetrad linear, functional megaspore single, chalazal, lacking sporopollenin, megasporangium indehiscent; pollen grains landing on ovule; male gametophyte development initially endosporic, lacking chlorophyll, tube developing from distal end of grain, gametes two, developing after pollination, with cell walls; female gametophyte endosporic, initially syncytial, walls then surrounding individual nuclei; seeds "large" [ca 8 mm3], but not much bigger than ovule, with morphological dormancy; embryo cellular ab initio, endoscopic, plane of first cleavage of zygote transverse, suspensor +, short-minute, embryonic axis straight [shoot and root at opposite ends; plant allorhizic], white, cotyledons 2; plastid transmission maternal; ycf2 gene in inverted repeat, whole nuclear genome duplication [zeta duplication], 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.

ANGIOSPERMAE / MAGNOLIOPHYTA

Lignans, O-methyl flavonols, dihydroflavonols, triterpenoid oleanane, 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, exodermis +; shoot apex with tunica-corpus construction, tunica 2-layered; reaction wood ?, associated gelatinous fibres [g-fibres] with innermost layer of secondary cell wall rich in cellulose and poor in lignin; 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 cell and sieve tube from same mother cell; sugar transport in phloem passive; nodes 1:?; stomata brachyparacytic [ends of subsidiary cells level with ends of pore], outer stomatal ledges producing vestibule, reduction in stomatal conductance to increasing CO2 concentration; lamina formed from the primordial leaf apex, margins toothed, development of venation acropetal, overall growth ± diffuse, venation hierarchical-reticulate, secondary veins pinnate, veins (1.7-)4.1(-5.7) mm/mm2, endings free; most/all leaves with axillary buds; flowers perfect, pedicellate, ± haplomorphic, parts spiral [esp. the A], free, numbers unstable, development in general centripetal; P +, members 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], ± embedded in the filament, with at least outer secondary parietal cells dividing, each theca dehiscing longitudinally, endothecium +, endothecial cells elongated at right angles to long axis of anther; (tapetum glandular), cells binucleate; microspore mother cells in a block, microsporogenesis successive, walls developing by centripetal furrowing; pollen subspherical, tectum continuous or microperforate, ektexine columellate, endexine +, thin, compact, lamellate only in the apertural regions; nectary 0; carpels present, superior, free, several, ascidiate, with postgenital occlusion by secretion, stylulus short, hollow, cavity not lined by distinct epidermal layer, stigma ± decurrent, carinal, 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, functional megaspore, chalazal, lacking cuticle; female gametophyte four-celled [one module, nucleus of egg cell sister to one of the polar nuclei]; supra-stylar extra-gynoecial compitum +; ovule not increasing in size between pollination and fertilization; pollen grains landing on stigma, bicellular at dispersal, mature male gametophyte tricellular, germinating in less than 3 hours, pollination siphonogamous, tube elongated, growing 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 gametes lacking cell walls, flagellae 0, double fertilization +, ovules aborting unless fertilized; P deciduous in fruit; seed exotestal, much larger than ovule at time of fertilization; endosperm diploid, cellular, heteropolar [micropylar and chalazal domains develop differently, 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; dark reversal Pfr → Pr; Arabidopsis-type telomeres [(TTTAGGG)n]; 2C genome size 1-8.2 pg [1 pg = 109 base pairs], whole nuclear genome duplication [epsilon duplication]; protoplasm dessication tolerant [plant poikilohydric]; 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]].

[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]]]]: vessel elements with scalariform perforation plates in primary xylem; essential oils in specialized cells [lamina and P ± pellucid-punctate]; tension wood +; tectum reticulate; anther wall with outer secondary parietal cell layer dividing; carpels plicate; nucellar cap + [character lost where in eudicots?]; 12BP [4 amino acids] deletion in P1 gene.

[[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]]] / MESANGIOSPERMAE: benzylisoquinoline alkaloids +; sesquiterpene synthase subfamily a [TPS-a] [?level], polyacetate derived anthraquinones + [?level]; outer epidermal walls of root elongation zone with cellulose fibrils oriented transverse to root axis; P more or less whorled, 3-merous [possible position]; pollen tube growth intra-gynoecial; embryo sac bipolar, 8 nucleate, antipodal cells persisting; endosperm triploid.

[MONOCOTS [CERATOPHYLLALES + EUDICOTS]]: (extra-floral nectaries +); (veins in lamina often 7-17 mm/mm2 or more [mean for eudicots 8.0]); (stamens opposite [two whorls of] P); (pollen tube growth fast).

[CERATOPHYLLALES + EUDICOTS]: ethereal oils 0.

EUDICOTS: (Myricetin, delphinidin +), asarone 0 [unknown in some groups, + in some asterids]; root epidermis derived from root cap [?Buxaceae, etc.]; (vessel elements with simple perforation plates in primary xylem); nodes 3:3; stomata anomocytic; flowers (dimerous), cyclic; K/outer P members with three traces, ("C" +, with a single trace); A few, (polyandry widespread, initial primordia 5, 10, or ring, ± centrifugal), filaments fairly slender, anthers basifixed; microsporogenesis simultaneous, pollen tricolpate, apertures in pairs at six points of the young tetrad [Fischer's rule], cleavage centripetal, wall with endexine; G with complete postgenital fusion, stylulus/style solid [?here]; seed coat?

[PROTEALES [TROCHODENDRALES [BUXALES + CORE EUDICOTS]]]: (axial/receptacular nectary +).

[TROCHODENDRALES [BUXALES + CORE EUDICOTS]]: mitochondrial rps2 gene lost.

[BUXALES + CORE EUDICOTS]: ?

CORE EUDICOTS / GUNNERIDAE: (ellagic and gallic acids +); leaf margins serrate; compitum + [one place]; micropyle?; whole nuclear genome duplication [palaeohexaploidy, gamma triplication], PI-dB motif +, small deletion in the 18S ribosomal DNA common.

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; P = calyx + corolla, 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, internal/adaxial to the corolla whorl, 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]; RNase-based gametophytic incompatibility system present; floral nectaries with CRABSCLAW expression.

[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 m.y. for relaxed and constrained penalized likelihood crown-group ages, comparable ages in Moore et al. (2010: 95% HPD) were (104-)101(-96) m.y..

BERBERIDOPSIDALES Doweld   Main Tree.

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

Note: Possible apomorphies are in bold. However, the actual level at which many of these features, particularly the more cryptic ones, should be assigned is unclear. This is partly because many characters show considerable homoplasy, in addition, basic information for all too many 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 is the not-so-trivial issue of how ancestral states are reconstructed (see above).

Evolution. Magallón and Castillo (2009) estimate ages of ca 112.5 and 113.1 m.y. for relaxed and constrained penalized likelihood datings respectively for the divergence of stem Berberidopsidales and ca 88.7 and 88.9 m.y. for crown divergence (relaxed and constrained again).

This clade has notably large seeds (Moles et al. 2005a; Sims 2012: 1 species measured).

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, if Santalales are basal to Berberidopsidales in the clade immediately leading to the asterids, as in Moore et al. (2010), the significance of such features is less unclear (see also Ronse de Craene & Brockington 2013; Doyle 2013).

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 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.

Synonymy: Berberidopsidanae Thorne & Reveal

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

Aextoxicaceae

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 and internal to A; staminate flowers: stamens = and opposite sepals, filaments relatively stout; G vestigial; carpellate flowers: staminodia +; G 1, stylulus 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 [ca 13 cells across?], 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 ± transverse, long, curved, 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]

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 (Ronse DeCraene & Stuppy 2010: a flower with two carpels was once seen). 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 (1936a), 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), or linked with Saxifragales (Qiu et al. 1998).

BERBERIDOPSIDACEAE Takhtajan   Back to Berberidopsidales

Berberidospidaceae

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 +, spiral, (9-)12(-15), all except the outer petal-like, 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.]

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, not on placentae as in Salicaceae and Achariaceae. In Streptothamnus there is no necariferous disc - 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.