EMBRYOPSIDA Pirani & Prado
Gametophyte dominant, independent, multicellular, initially ±globular, not motile, branched; showing gravitropism; glycolate oxidase +, glycolate metabolism in leaf peroxisomes [glyoxysomes], 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; 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, asymmetrical; 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 [= 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 more or less inclusive clades 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 +); borate cross-linked rhamnogalactan II, xyloglucans with side chains uncharged [?level], in secondary walls of vascular and mechanical tissue; lignins +; roots +, often ≤1 mm across, 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 in strobili, sporangia adaxial, columella 0; tapetum glandular; sporophyte-gametophyte junction lacking dead gametophytic cells, mucilage, ?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]; embryo 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 [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 axillary, buds exogenous; lateral root origin from the pericycle; cork cambium + [producing cork abaxially], vascular cambium bifacial [producing phloem abaxially and xylem adaxially].
SEED PLANTS† / SPERMATOPHYTA†
Growth of plant bipolar [plumule/stem and radicle/root independent, roots positively geotropic]; 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, free-nuclear/syncytial to start with, walls then coming to surround the individual nuclei, process proceeding centripetally.
EXTANT SEED PLANTS
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]; roots often ≥1 mm across, stele diarch to pentarch, xylem and phloem originating on alternating radii, cork cambium deep seated, gravitropism response fast; 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.; branching by 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; embryo cellular ab initio, suspensor short-minute, embryonic axis straight [shoot and root at opposite ends], primary root/radicle produces taproot [= 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 event], 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; epidermis probably originating 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, multiseriate rays +, wood parenchyma +; sieve tubes enucleate, sieve plates 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 guard cells], 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; P = 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 restricted to 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, egg and polar nuclei sisters]; 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 (ca 10-)80-20,000 µm h-1, tube 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; fruit indehiscent, P deciduous; mature seed much larger than fertilized ovule, small [<5 mm long], dry [no sarcotesta], exotestal; endosperm +, ?diploid [one polar nucleus + male gamete], 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 IR expansions, 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.
[[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 [?here]; pollen tube growth intra-gynoecial; extragynoecial compitum 0; carpels plicate [?here]; embryo sac monosporic [spore chalazal], 8-celled, bipolar [Polygonum type], antipodal cells persisting; endosperm triploid.
[MONOCOTS [CERATOPHYLLALES + EUDICOTS]]: (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 [or next node up]; fruit dry [very labile].
EUDICOTS: (Myricetin +), 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; protandry common; K/outer P members with three traces, ("C" +, with a single trace); A ?, 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], short [<2 x length of ovary]; seed coat?; palaeotetraploidy event.
[PROTEALES [TROCHODENDRALES [BUXALES + CORE EUDICOTS]]]: (axial/receptacular nectary +).
[TROCHODENDRALES [BUXALES + CORE EUDICOTS]]: benzylisoquinoline alkaloids 0; euAP3 + TM6 genes [duplication of paleoAP3 gene: B class], mitochondrial rps2 gene lost.
[BUXALES + CORE EUDICOTS]: mitochondrial rps11 gene lost.
CORE EUDICOTS / GUNNERIDAE: (ellagic and gallic acids +); leaf margins serrate; compitum + [one position]; micropyle?; γ genome duplication [allopolyploidy, 4x x 2x], x = 3 x 7 = 21, 2C genome size (0.79-)1.05(-1.41) pg, PI-dB motif +; small deletion in the 18S ribosomal DNA common.
[ROSIDS ET AL. + ASTERIDS ET AL.] / PENTAPETALAE / [SANTALALES, CARYOPHYLLALES, SAXIFRAGALES, DILLENIALES, VITALES, ROSIDAE, [BERBERIDOPSIDALES + ASTERIDAE]: root apical meristem closed; (cyanogenesis also via [iso]leucine, valine and phenylalanine pathways); flowers rather stereotyped: 5-merous, parts whorled; P = K + C, K enclosing the flower in bud, with three or more traces, odd K adaxial, C with single trace; A = 2x K/C, in two whorls, alternating, (many, but then usually fasciculate and/or centrifugal); pollen tricolporate; G [(3, 4) 5], when 5 opposite K, whorled, placentation axile, style +, stigma not decurrent, compitum + [one position]; endosperm nuclear/coenocytic; fruit dry, dehiscent, loculicidal [when a capsule]; floral nectaries with CRABSCLAW expression, RNase-based gametophytic incompatibility system present.
Phylogeny. Prior to the seventh version of this site asterids were part of a major polytomy that included rosids, Berberidopsidales, Santalales, and Caryophyllales, but then the order of branching below the asterids seemed to be stabilizing, perhaps with a clade [Berberidopsidales [Santalales [Caryophyllales + Asterids]]] while rosid relationships seemed to be [Saxifragales [Vitales + Rosids]]]. However, recent work suggests a polytomy is indeed probably the best way to visualize relationships around here at present. So for further discussion of relationships at the base of asterids and rosids, see the Pentapetalae node.
[BERBERIDOPSIDALES + ASTERIDAE]: ?
ASTERIDAE / ASTERANAE Takhtajan: nicotinic acid metabolised to its arabinosides; (iridoids +); tension wood decidedly uncommon; C enclosing A and G in bud, (connate [sometimes evident only early in development, petals then appearing to be free]); anthers dorsifixed?; if nectary +, gynoecial; G , style single, long; ovules unitegmic, integument thick [5-8 cells across], endothelium +, nucellar epidermis does not persist; exotestal [!: even when a single integument] cells lignified, esp. on anticlinal and/or inner periclinal walls; endosperm cellular.
[LAMIIDAE/ASTERID I + CAMPANULIDAE/ASTERID II] / CORE ASTERIDS / EUASTERIDS / GENTIANIDAE: plants woody, evergreen; ellagic acid 0, non-hydrolysable tannins not common; vessel elements long, with scalariform perforation plates; sugar transport in phloem active; inflorescence usu. basically cymose; flowers rather small [<8 mm across]; C free or basally connate, valvate, often with median adaxial ridge and inflexed apex ["hooded"]; A = and opposite K/P, free to basally adnate to C; G [#?]; ovules 2/carpel, apical, pendulous; fruit a drupe, [stone ± flattened, surface ornamented]; ="apo">seed single; duplication of the PI gene.
ASTERID II / CAMPANULIDAE / [METTENIUSALES [BRUNIALES [ASTERALES [APIALES, DESFONTAINIALES, DIPSACALES, ESCALLONIALES, PARACRYPHIALES]]]]: myricetin 0; style shorter than the ovary; endosperm copious, embryo short/very short.
[BRUNIALES [ASTERALES [APIALES, DESFONTAINIALES, DIPSACALES, ESCALLONIALES, PARACRYPHIALES]]] / APIIDAE: tube initiation early; G inferior, , style long.
[ASTERALES [APIALES, DESFONTAINIALES, DIPSACALES, ESCALLONIALES, PARACRYPHIALES]] / CORE CAMPANULIDS: C forming distinct tube; A epipetalous.
[APIALES, DESFONTAINIALES, DIPSACALES, ESCALLONIALES, PARACRYPHIALES]: ?
The next few paragraphs probably to be removed to Asterales node...
Age. Magallón and Castillo (2009) offer estimates of 96-94 Ma for crown-group ages and Magallón et al. (2015: note topology) an age of around 93.7 Ma, K. Bremer et al. (2004a: note topology) an age of ca 114 Ma and Wikström et al. (2015: note topology) an age of (110-)101(-90) Ma, Foster et al. (2016a: q.v. for details) an age of around 98 Ma, Bell et al. (2010: note topology) ages of (94-)84, 77(-69) Ma, Nylinder et al. (2012: suppl.) an age of ca 68.8 Ma, N. Zhang et al. (2012) suggested ages of (89-)74(-52) Ma, Xue et al. (2012) an age of 67.3-64.2 Ma, Naumann et al. (2013) an age of around 82.9 Ma, while Beaulieu et al. (2013a: 95% HPD) estimated an age of (109-)99(-89) My; the age of this node is around 111 Ma in Z. Wu et al. (2014: note topology) or 111-98 Ma in J. Wang et al. (2020).
Evolution: Divergence & Distribution. Divergence at this node probably occurred in plants growing in the southern hemisphere (Beaulieu et al. 2013a).
Taxa with relatively small flowers that are aggregated into conspicuous flower-like inflorescences (but c.f. Campanulaceae, etc.; see Leins & Erbar 2010: fig 157) are common in all three large orders in this clade, the apices of the petals tend to be pointed (not in Aquifoliaceae), and valvate corollas are common. The feature "small flowers" itself may be assignable to the gentianid node, since the first nodes of both the lamiid and campanulid clades may have this feature.
Changes in seed/disseminule unit (simply "seeds" below) size may be pegged to this node. Seeds of this clade are generally rather small, perhaps connected with the herbaceous-shrubby habit and the small flowers, both common here (see also Moles et al. 2005a; Linkies et al. 2010), and contrast with the larger seeds of most Aquifoliales, Icacinales, etc., groups that tend to have larger plants. Haig and Westoby (1991) discuss situations in which small seeds may be at an advantage. Overall diversification rates are higher in smaller- than larger-seeded angiopserms, perhaps linked to improved colonization potential (Igea et al. 2017), and the rate of seed mass change is also higher when rates of diversification are higher. For further discussion about seed size, see core lamiids and core asterids.
The evolution of an inferior ovary might be a key innovation (Endress 2011a). Although an inferior ovary may be developmentally connected with how the corolla tube develops, i.e., with early initiation of the tube (e.g. Ronse Decraene & Smets 2000), the position of this latter feature on the tree is uncertain. Several core campanulid families have this kind of initiation, but not only is sampling within larger orders poor and within smaller orders close to non-existent, in the lamiids both Oleaceae (superior ovary) and Rubiaceae (inferior ovary), basal or almost so in their orders (Lamiales and Gentianales respectively), may have early initiation, and corolla initiation in Aquifoliales and basal clades in the lamiids is largely unknown (Leins & Erbar 2003b for a summary). Taxa with more or less superior ovaries are scattered throughout the core campanulids, e.g. Sphenostemon (Paracryphiales-Paracryphiaceae), Pittosporaceae (Apiales), Rousseaceae-Carpodetoideae and Phellinaceae (Asterales), Desfontaineales, etc., while in Adoxaceae, sister to other Dipsacales, the ovary is semi-inferior, Ying et al. (1993) even describing the ovary of Tetradoxa as being superior. It will be interesting to find out about corolla development in such taxa.
Genes & Genomes. The I copy of the RPB2 gene is lost in most members of this clade (Oxelman et al. 2004; Luo et al. 2007), but it occurs both in Escalloniaceae and Apiales. However, clades like Paracryphiales and Bruniales (Lundberg 2001e) have not been sampled for this gene.
Chemistry, Morphology, etc.. Acetylenic fatty acids/polyacetylenes are sporadic in this clade (e.g. Erbar & Leins 2004; Leins & Erbar 2004b), occurring in Asterales, Dipsacales and Apiales, but always in much embedded clades. These similarities are probably parallelisms. Although iridoids and polyacetylenes usually do not co-occur, the two are sometimes to be found together, as in Torricellia angulata (Pan et al. 2006; Liang et al. 2009).
Phylogeny. For the relationships of Escalloniales, see the asterid II/gentianid clade.
ESCALLONIALES Martius - Main Tree.
Just the one family, 10 genera, 131 species.
Note: In all node characterizations, boldface denotes a possible apomorphy, (....) 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 precise 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).
Synonymy: Escalloniineae Shipunov - Tribelales Doweld
ESCALLONIACEAE Dumortier, nom. cons. - Back to Escalloniales
Plants Al accumulators; iridoid ?type; ?nodes; inflorescence racemose; C free; A not adnate to C, anthers basifixed; nectary +; ovule with integument 5-10 cells across; x = 12, nuclear genome [1 C] (0.08)0.512(-3.272) pg.
7 [list] /135 (103) - five groups below. Scattered: Réunion, E. Himalayas and S. China to E. and W. Australia and New Zealand, Central and South America.
Age. The crown age for this family is in excess of 110 Ma (K. Bremer et al. 2004a: note topology) or (104-)88(-67) Ma (Wikström et al. 2015).
1. Polyosma Blume
Trees; plants Al accumulators; iridoids +; wood storying +; vessel elements with scalariform perforation plates; pericycle with sclereids; nodes 1:1; petiole bundle?; stomata ?; hairs unicellular; leaves opposite, lamina margins toothed (entire); flowers 4-merous; K connate, C valvate, (± coherent); pollen triporate; G , placentation intrusive parietal, stigma capitate, bilobed; ovules many/carpel, straight, integument 4-10 cells across, ?endothelium, parietal tissue ca 1 cell across[?], nucellus base massive; (megaspore mother cells several); fruit a 1-seeded drupe; endosperm starchy, thick-walled, ?haustoria, embryo short, undifferentiated; n = ?
1/80. E. Himalayas and S. China to E. Australia and New Caledonia (map: in part from GBIF Data Portal 3.i.2009).
Synonymy: Polyosmaceae Blume
2. Escallonia L. f., Valdivia J. Rémy, Forgesia de Jussieu
Shrubs to trees (annual herbs); route I seco- and route II decarboxylated iridoids, flavonols +; (cork cambium deep-seated - Escallonia); sclereids forming pericyclic sheath - Forgesia); nodes 1:1, 3:3 [Escallonia]; petiole bundle arcuate; (heads of glandular hairs with radially arranged cells); stomata anomocytic; lamina vernation supervolute (conduplicate), margins with broad glandular teeth and two accessory veins (entire); flowers 5-9-merous; C contorted, (± connate - Escallonia); anthers placentoid +; ?pollen; G [2-4], (largely superior), collateral, or median member adaxial, placentation parietal, style ± branched or not, stigma punctate to capitate or clavate-lobed, wet; ovule 1-many/carpel, (ascending), integument 5-8 cells across, micropyle long, endothelium +/weak; embryo sac protruding at micropyle; capsule septicidal, often splitting down the sides; exotestal cells with inner walls thickened and lignified (not), elongated or not, meso- and/or endotesta usu. persist; micropylar endosperm haustoria +, (embryo long); n = 12, nuclear genome [1C] 0.42-0.57(- 6.15 - ?polyploid) pg.
3/42: Escallonia (40). Scattered, but largely southern: Central and South America, Réunion (map: from Sleumer 1968; FloraBase 2007). [Photos - Escallonia Flower, Valdivia Flower.]
Age. The appproximate crown-group age for this clade - the [Eremosyne + Escallonia] node - is (85-)80, 72(-67) Ma - see Wikström et al. (2001), or (87-)72, 65(-48) Ma - see Bell et al. (2010).
3. Eremosyne L. f.
Annual rosulate herb; ?iridoids; vascular stele with separate bundles; nodes 1:1; lamina margins entire, those of inflorescence bracts more or less lobed, venation palmate-acrodromous; inflorescence branches cymose; flowers small; K valvate; pollen with incomplete tectum and complex endaperture; ?nectary; G , largely superior, style branches long; 1 ovule/carpel, ascending, epitropous, campylotropous; capsule loculicidal; testa cells somewhat elongated, subpapillate; embryo short; n = 9.
1/1: Eremosyne pectinata S.W. West Australia (see map above).
Synonymy: Eremosynaceae Dandy
4. Tribeles Philippi, Rayenia Menegoz & A. E. Villarroel
Small, prostrate shrub; ?iridoids; ?nodes; plant glabrous; lamina with three small teeth at the apex, or margin serrulate/long setose, base ± broad; flowers terminal, solitary; K ± truncate, C ± contorted or imbricate; anthers basifixed/broadly dorsifixed, extrorse; ?nectary; G [3, 5 - Rayenia], stigma three-lobed, subclavate/disciform, barely lobed; ovules several/carpel, bitegmic; capsule loculicidal or septicidal, K persistent; seeds shiny, remaining attached to the columella, ribbed [Rayenia]y; testa cells polygonal, palisade; n = ?
2/2. Southern Andes (S. Chile, Argentina).
Synonymy: Tribelaceae Airy Shaw
5. Anopterus Labillardière
Shrubs; nodes 3:3; plant glabrous; lamina margin serrate; flowers 6-9-merous; C imbricate; G , placentation parietal; ovule with long micropyle; capsule septicidal; seeds winged; testa to 7 cells across, exotestal cells elongated, inner walls thickened; n = ?
1/2: Eastern Australia, Tasmania (see map above).
Synonymy: Anopteraceae Doweld
Evolution: Genes & Genomes. Escallonia lacks the mitochondrial coxII.i3 intron; other taxa have not been sampled.
Chemistry, Morphology, etc.. Escallonia occasionally has prickles in the stipular position.
For anatomy, see Gornall et al. (1998) and Gornall and Al-Shammary (1998: Eremosynaceae), for some information on ovules, see Mauritzon (1933). For anatomy of Forgesia, see Ramamonjiarisoa (1980). For Escallonia, see Stern (1974: anatomy), Swamy (1954: nodes), Al-Shammary and Gornal (1994: indumentum), Krach (1976) and Nemirovich-Danchenko and Lobova (1998), both seeds, and Schnizlein (1843-1870: fam. 170: floral orientation). Much other general information is taken from Lundberg (2001c: Polyosmaceae, 2001d: Escalloniaceae, 2016), while for some information on embryology and seed, see Mauritzon (1933, 1938a) and Danilova (1996. For a summary of information on Eremosyne (?ovules not quite tenuinucellate), see Hibsch-Jetter et al. (1997) and Conran and Macfarlane (2016), also Gornall and Al-Shammary (1998: anatomy).
A very heterogeneous and poorly known group. As Bensel and Palser (1975d: p. 693, see also 1975c) noted of Escallonioideae (for them, also including Quintinia [= Paracryphiales-Paracryphiaceae]), "The only conclusion that can be drawn about Escallonioideae is that it has been too little investigated in all aspects" - a conclusion that has so far unfortunately stood the test of time.
Phylogeny. A relationship between Escalloniaceae s. str. and Eremosynaceae has strong 3-gene support (Soltis et al. 2000; see also Hibsch-Jetter et al. 1997); a further association with Tribelaceae is only weakly supported (Savolainen et al. 2000b: rbcL alone). However, Escalloniaceae were found to be paraphyletic if Eremosynaceae and Tribelaceae were excluded (or Anopterus would have to be in a separate family), furthermore, the monogeneric Polyosmaceae were sister to the whole group (Lundberg 2001e: three-gene Bayesian analysis); K. Bremer et al. (2004a) recovered the relationships [[Tribeles + Polyosma] [Escallonia + Eremosyne]]. Details of relationships between the genera remain unclear (Tank & Donoghue 2010, see also Beaulieu et al. 2013a, but sampling). Sede et al. (2013) found strong support for [Valdivia (Chile) + Forgesia (Reunion)] as sister to Escallonia (see also Tank & Donoghue 2010; Zapata 2012; Villarroel et al. 2021); although Eremosyne was sister to the rest of the family, apparent differences from Bremer et al. (2004a) may be a rooting problem. One set of relationships in Wikström et al. (2015) is [[Polyosma + Escallonia] [Eremosyne + Tribeles]], but with little support, in another analysis Polyosma was sister to the other genera of Escalloniaceae. In general, apart from the [[Valdivia + Forgesia] Escallonia] clade, relationships in the family seem unclear (Villarroel et al. 2021).
Polyosma linked with Quintinia (Paracryphiales) in an analysis of mitochondrial genes, but not with other genes; this is probably because of horizontal transfer of the mitochondrial genome from Quintinia to Polyosma (Soltis et al. 2011).
For the phylogeny of Escallonia, see Zapata (2013) and Sede et al. (2013), there is considerable geographical structuring of relationships.
Classification. Lundberg (pers. comm.) thought that all these families should be combined into one, and so they are (see also A.P.G. III 2009).
Previous Relationships. Krach (1976, 1977) suggested that Escalloniaceae, in which he included Abrophyllaceae and Argophyllum (Rousseaceae), both in Asterales here, were close to Hydrangeaceae, and should be placed in an Escalloniales; Escalloniaceae were placed in Hydrangeales by Takhtajan 1997), although he wasn't sure about the position of Anopterus. Eremosyne was previously frequently included in Saxifragaceae (e.g. Cronquist 1981) or Saxifragales (Takhtajan 1997). Tribeles was placed in Hydrangeales by Takhtajan (1997), who described the capsule as being loculicidal.
Thanks. I am grateful to F. Zapata for discussion.