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; sporophyte dependent on gametophyte, 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.
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; sporophyte-gametophyte junction interdigitate, sporophyte cells showing rhizoid-like behaviour.
Sporophyte branched, branching apical, dichotomous; sporangia several; spore walls not multilamellate [?here].
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 soon independent, dominant, 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 ± indeterminate; 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].
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; 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; branches axillary (buds not associated with all leaves), exogenous; 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; gametophytes dependent on sporophyte; male gametophyte development initially endosporic, 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]]: benzylisoquinoline alkaloids 0; euAP3 + TM6 genes [duplication of paleoAP3 gene: B class], 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 , G  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; (monosymmetric flowers with adaxial/dorsal CYC expression).
Age. The age of this clade has been estimated at some 113 m.y. (Leebens-Mack et al. 2005, but see sampling); Anderson et al. (2005) suggest a similar figure (stem group to 116 m.y. old, crown group diversification by ca 109 m.y.); Chaw et al. (2004: 61 chloroplast genes, sampling poor) date the crown group to 115-110 m.y.a., and Magallón and Castillo (2009) to around 114.5 m.y.. Moore et al. (2010: 95% highest posterior density, see also N. Zhang et al. 2012) suggest crown-group ages of (113-)109(-104) m.y., Bell et al. (2010) ages of (124-)121, 117(-97) m.y., and Magallón et al. (2013: with temporal constraints) ages of (115.9-)110.5-109(-103) m.y. for this clade. Xue et al. (2012: Dilleniaceae not included) suggest the youngest age - 104.7-101.6 m.y. ago.
The oldest known core eudicot macrofossil, unfortunately not attributed to any extant group, is the Rose Creek fossil from the Cretaceous-Cenomanian, a mere 96-94 m.y.a. (Basinger & Dilcher 1984). The flower is relatively large compared to the tiny flowers so common in early Cretaceous angiosperms. The five stamens are opposite the petals and there is a well developed nectary, the earliest recorded in the fossil record (Friis et al. 2011).
Evolution. Divergence & Distribution. It is worth repeating that the positions of possible apomorphies/key innovations, much discussed in the context of the Pentapetalae node, are unclear. Again, basic information for all too many critical taxa is incomplete, and the basic morphology of Proteales may be of particular importance in this context. There is also some uncertainty about relationships in the tree between Ranunculales and Gunnerales.
Endress (2011a) suggested that the presence of compitum in rosids and the extended clade including asterids might be key innovations for each; Dilleniaceae do not have a compitum. It seems preferable to peg the character at this node; Dilleniaceae would then have lost a compitum, although if Dilleniaceae turn out to be sister to the combined clades, things will be simpler. However, Gunneraceae, at least, also have a compitum, and so one can argue that presence of compitum could be placed one node more basally... Five-merous flowers and the distinction between sepals and petals are other potential key innovations, whatever the position of Dilleniaceae (Endress 2011a).
The flowers of Pentapetalae are very distinctive, as indicated by the characterisation above. Five-merous flowers preponderate (hence the name "pentapetalae"), and they are uncommon in more basal clades (González & Mello 2009). Compared to many eudicots in more basal clades, the two perianth whorls are distinctive in that members of each encircle the floral axis, all members of the androecial whorls being adaxial/interior to the petals. Sepals usually have three traces and petals have one, while three-trace petals are sometimes to be found in other eudicots, magnoliids, etc. There has been much discussion as to the distinction between and evolution of sepals and petals. Petals here may generally be derived from tepals, perhaps ultimately from bracts, not from stamens (perhaps with some exceptions, as in Caryophyllaceae, etc.: Ronse de Craene 2007, 2008). The duplication of a number of genes important in determining the identity of the parts of pentapetalous flowers (AP3, AP1, SEP, AG) may be connected with the gamma genome triplication event that is an apomorphy for the core eudicots (Jiao et al. 2012; Vekemans et al. 2012). For monosymmetry and the patterns of CYC gene expression, see Hileman (2014); denser sampling is much needed!
Taxa that have flowers with many stamens are scattered throughout the core eudicots. The stamens usually develop on common primordia, whether a ring primordium or five or ten separate primordia, when five, the primordia are often opposite the petals, rather than alternating with them. Numerous individual stamens then develop from these few initial primordia, and development is often centrifugal (c.f. esp. magnoliids and the ANITA grade). At maturity, the stamens themselves may be more or less connate or in fascicles (especially Corner 1946b; Weberling 1989; Leins 2000 and references; Prenner et al. 2008). There can be considerable variation in staminal development between closely related multistaminate taxa (e.g. Hufford 1990; Ge et al. 2007). Polyandry is decidedly less common in the euasterid clade (q.v. for discussion) and it appears to be linked with increases of numbers of petals and/or carpels, just one of the ways in which polyandry occurs here.
Tentatively, then, and based entirely on gross morphology, there seem to have been major changes in floral organisation at the angiosperm node, the monocot node, the commelinid node, the Pentapetalae node, the asterid node, and perhaps the euasterid node. As noted above, the floral morphology of extant Gunnerales is very different from that of Pentapetale and is more similar to that of the eudicots immediately basal to them.
For the floral development of Berberidopsis corallina and Aextoxicon (Berberidopsidales), possible "links" in the evolution of the flower of core eudicots, see Ronse De Craene (2004, 2007, 2010). The link is at best thought of as an analogy, since several elements of this floral morphology are probably parallelisms within core eudicots and others may even be reversals; there is also considerable variation in floral morphology in this small clade. Berberidospidales are part of the pectination immediately basal to asterids, relationships perhaps being [Santalales [Berberidopsidales [Caryophyllales + asterids]]] (see below). Chase (2005) noted that in Santalales some floral parts, particularly stamens, might have several whorls, and this perhaps suggested that canalisation of floral development there was less than in some other core eudicots; whether Santalales really are different in this respect from other core eudicot groups remains to be established. Clarification of the phylogenetic position of Dilleniales, etc. (see below), will undoubtedly help in our understanding of floral evolution.
Chemistry, Morphology, etc. The distribution of ellagic acid is similar to that of common primordium-type polyandry in the eudicots. Sampling of variation in the root apical meristem is poor, and possible reversals (for which, see Groot et al. 2004) have not been placed on the tree.
Lee et al. (2004) suggest that the CRABS CLAW gene is expressed in core eudicot nectaries (including extrafloral nectaries), or at least in the rosids and asterids that they sampled; it was not expressed in nectaries of Ranunculaceae; what happens in Proteaceae, which has axial nectaries, like rosids (e.g. Smets 1988) and Sabiaceae is unfortunately unknown. This gene is not expressed in the extrafloral nectaries of Passifloraceae (Krosnick et al. 2008a). Sucrose synthesis and secretion is similar in the nectaries of Brassicaceae and Solanaceae, extrastaminal and gynoecial nectaries respectively (Lin et al. 2014).
Phylogeny. This clade is strongly supported, e.g. Chase et al. (1993), D. Soltis et al. (1997, 1999, 2003a), Hoot et al. (1998), and Nandi et al. (1998), but support is rather weaker in Zhu et al. (2007). Within this large clade, although the rosid and asterid clades are well supported, other relationships have long been unclear, best being represented by a six-radiate polytomy (see the sixth and earlier versions of this site) involving Crossosomatales, Berberidopsidales, Caryophyllales, Santalales, rosids and asterids; Dilleniales and Saxifragales were also of uncertain positions. D. Soltis et al. (2003a: four-gene analysis) suggested that Berberidopsidales were sister to the rest of the non-rosid core eudicots, but they has only 54% jacknife support. Santalales were associated with asterids, while Saxifragales and Vitales linked with [Dilleniales + Caryophyllales], but with still less support (D. Soltis et al. 2003a). In some studies Dilleniaceae were sister to Caryophyllales, but with only very moderate support; D. Soltis et al. (2003a) provided rather stronger (83% jacknife) support for this position (see also Soltis et al. 2007a: 1.0 p.p.). It also seemed possible that [Caryophyllales + Dilleniales] and Santalales formed a clade (D. Soltis et al. 2000); Carlquist (2006) suggested that non-bordered perforation plates was a possible similarity between Santalales and Caryophyllales. Caryophyllales were linked with with asterids in a large 18S ribosomal DNA analysis (Soltis et al. 1997), albeit with only weak support (see also Hilu et al. 2003).
In studies using whole chloroplast genomes (Jansen et al. 2006a, esp. 2006b; Hansen et al. 2007; Cai et al. 2007; Ruhlman et al. 2006; Jansen et al. 2007; Moore et al. 2007; Logacheva et al. 2008) support for a [Caryophyllales + asterids] clade was stronger, however, Berberidospidales, Dilleniales, Santalales and Saxifragales were not included. [Caryophyllales + Santalales] were sister to asterids in some analyses in a study that focused on the position of Cynomoriaceae and Balanophoraceae (Nickrent et al. 2005: again, see sampling). In a study using the mitochondrial gene matR, Caryophyllales repeated as sister to asterids, but with very little support; in other analyses including a reduced sampling and two chloroplast genes Santalales and Dilleniales were also in this area, but again with little support (Zhu et al. 2007). In the combined morphological and molecular study of Nandi et al. (1998) the position of Caryophyllales was uncertain, but this was perhaps partly because the ovules of Rhabdodendraceae, there sister to all other Caryophyllales, were interpreted as being unitegmic; however, subsequent work suggested that Rhabdodendraceae are not sister to all other Caryophyllales, but are embedded in the order (see Caryophyllales page).
In any event, it was becoming increasingly likely that Caryophyllales, whether or not accompanied by a number of other taxa, were sister to asterids (but c.f. Goloboff et al. 2009). There was support for placing Crossosomatales as sister to the core malvid group (Huerteales, Sapindales, etc.: see Zhu et al. 2007; Soltis et al. 2011, etc.). In a two-gene study focussing of early-diverging eudicots, Dilleniales, Berberidopsidales, Santalales and Caryophyllales grouped in a pectinate fashion with the asterids, although support was low (Hilu et al. 2008). Wang et al. (2009: 12-gene plus plastid inverted repeat) in a study of the rosids found that Berberidopsidales was sister to a clade made up of the few Caryophyllales and asterids they had included. Moore et al. (2008) in a preliminary analysis of whole-chloroplast genome data, suggested that most members of the basal polytomy of the core eudicots could be placed as a series of pectinate branches immediately basal to the asterids; Moore et al. (2010, see also 2011) suggested the relationships [Santalales [Berberidopsidales [Caryophyllales + Asterids]]], the position of Caryophyllales having the least support (see also Arakaki et al. 2011; Ruhfel et al. 2014). Relationships in Bell et al. (2010) were [Berberidopsidales [Caryophyllales, Santalales, asterids]], in Soltis et al. (2011: little bootstrap support), [Santalales [[Berberidopsidales + Caryophyllales] + asterids]], i.e. their superasteridae. The transcriptome analyses of Wickett et al. (2014) also placed Caryophyllales in this area. All this is consistent with many of the earlier, more tentatively suggested relationships. However, a recent concatenated analysis of 110 single-copy protein sequences suggested that Beta vulgaris (Caryophyllales) was sister to a [rosid + asterid] clade (Dohm et al. 2013), but there may be methodological (see Xi et al. 2013b) and sampling issues at work here. Moreover, mitochondrial and nuclear genes placed Caryophyllales within rosids s.l., although support for this position was underwhelming (Sun et al. 2014).
Some morphological evidence, including seed coat anatomy, might suggest a specific relationship between Dilleniales and Vitales. However, Horne (2006) listed a number of features linking Dilleniaceae and Rhabdodendraceae (then thought to be sister to the rest of Caryophyllales), some of which could be features of [Dilleniales + Caryophyllales], and the status of the others depended on an improved resolution of relationships. These features include absence of tension wood; successive cambia present; vessel elements with simple perforation plates; wood with SiO2 bodies; nodes 3 or more:3 or more; leaves spiral; K persistent in fruit. Other work suggests that Rhabdodendraceae are sister to the core Caryophyllales and immediately associated families rather than sister to all Caryophyllales (e.g. Drysdale et al. 2007; Brockington et al. 2007), so the significance of these morphological similarities is unclear.
The position of Dilleniales has remained uncertain. Bell et al. (2010) placed it sister to Caryophyllales and Soltis et al. (2011) in a broadly similar position as sister their superasteridae, and with 87% ML bootstrap support; this position was also found by Arakaki et al. 2011), who included a larger sample of caryophyllalean chloroplast genomes. Similarly Qiu et al. (2010) found a weakly supported [Dilleniales + Berberidopsidales] clade sister to an [asterid [Santalales + Caryophyllales]] clade, but also with very weak support. Moore et al. (2008) and Ruhfel et al. (2014: not amino acid analyses - sister to asterids) suggested that Dilleniales were sister to rosids, although support could be stronger, while Moore et al. (2011) found a weakly supported [Dilleniales [rosids s.l. + asterids s.l.]] clade. Finally, in an analysis of 18S/26S nuclear ribosomal data the clades [Dilleniales + Celastrales] and [Caryopyllales + Zygophyllales] were recovered embedded in the rosids, but with vanishingly little support, while there was some support for the position of Santalales as sister to all other Pentapetalae, and little support for Berberidopsidales as sister to the remaining Pentapetalae (Maia et al. 2014). Dilleniaceae are near basal somewhere in Pentapetalae, but are best left unplaced for now.
For further discussion, see asterids, and Saxifragales.
Classification. In Versions 8 and earlier of this site this was called the the core eudicot clade, largely because the evolution of the "typical" core eudicot flower can be pegged to this node; the current delimitation of core eudicots refers to a clade that is molecularly well supported but that is perhaps morphologically less interesting.
[DILLENIALES [SAXIFRAGALES [VITALES + ROSIDS s. str.]]]: stipules + [usually apparently inserted on the stem].
Evolution. Moore et al. (2010: 95% highest posterior density) suggest ages of (112-)108(-103) m.y. for the crown group.
DILLENIALES Berchtold & J. Presl Main Tree.
A many, often centrifugal; G separate, compitum 0; ?micropyle; fruit a follicle; endotesta ± palisade, massively lignified, exotegmen usu. tracheidal. - 1 family, 10 genera, 300 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).
Synonymy: Dillenianae Takhtajan - Dilleniidae Reveal & Takhtajan
DILLENIACEAE Salisbury Back to Dilleniales
Trees and shrubs (lianes, perennial herbs); distinctive flavonols, myricetin, ellagic acid +; hairs ± stellate [esp. Hibbertia] and sclerified; primary stem with continuous vascular cylinder; (successive cambia +); cork cambium deep-seated; (vessel elements with simple perforation plates); true tracheids +; raphides +, also common in wood; rays often broad; ?nodes; epidermis silicified; branching from previous flush; hairs unicellular; leaves spiral, lamina vernation conduplicate, surface often scabrid, margins toothed, secondary veins parallel, proceeding straight to the teeth [percurrent], tertiary venation ± scalariform, fine veins areolate, teeth with clear glandular expanded apex, base rather broad, stipules 0, long petiolar flanges + (0); inflorescence?; pedicels articulated; flowers often yellow; K (3-)5(-20), (with 1 trace), large, C (2-)5, crumpled in bud (not); androecium often asymmetric, A (2-)many, from a ring primordium or fasciculate, fascicles opposite K, supplied by trunk bundles, (staminodes +), connective often well-developed, anthers basifixed, (dehiscing by pores), exodermis well developed; (pollen colpate); nectary 0; G (1-3)4-8[-20], (opposite petals, or odd member adaxial), styluli long, stigmas capitate to punctate, wet [1 record]; ovules 1-many/carpel, apotropous, often campylotropous (straight), micropyle zigzag or exostomal, outer integument 2(-3) cells across, inner integument 2-6 cells across, parietal tissue 6-14 cells across, nucellar cap ca 2 cells across, chalazal area massive; (megaspore mother cells several); (fruit a nut; berry), K persistent in fruit (accrescent, enclosing fruit, ± fleshy); aril +, funicular, often laciniate, exotesta often fleshy, exotegmen with spiral or annular thickenings, endotegmen tanniniferous; zygote with distinctive wall and protrusions into the endosperm ["mantle"]; n = 4, 5, 8-10, 12, 13; germination phanerocotylar.
10[list]/300-410 - four groups below. Tropical and warm temperate (map: from van Steenis & van Balgooy 1966; van Balgooy 1975; Heywood 1978; Trop. Afr. Fl. Pl. Ecol. Distr. 1. 2003; Horn 2009). [Photos - Collection.]
Age. The stem age may be ca 114.75 m.y. and the crown age only ca 52.5 m.y. (Magallón & Castillo 2009).
1. Delimoideae Burnett
Lianes; stomata paracytic.
1/44 (Tetracera). Pantropical.
[Doliocarpoideae [Hibbertioideae + Dillenioideae]]: ?
2. Doliocarpoideae J. W. Horn
(Compitum +), stigma infundibular; ovules 2/carpel, collateral, one epitropous, the other apotropous.
5/65: Doliocarpus (40). Neotropical.
[Hibbertioideae + Dillenioideae]: ?
3. Hibbertioideae J. W. Horn
Nodes 3:3; (hairs stellate); (lamina entire), tertiary venation ± random, areoles at most weakly developed; (flowers [horizontally] monosymmetric); A 1-200+ (outer staminodes +; obdiplostemonous, the outer A basally connate).
1/115-225. Madagascar to Fiji, but nearly all endemic to Australia.
4. Dillenioideae Burnett
Cork cambium superficial; nodes 1:1; leaf base surrounding stem; (flowers [horizontally] monosymmetric); A very numerous [200+]; G many, (compitum +); (exotestal cells large, tanniniferous, becoming flattened - Dillenia).
4/75. Dillenia (60). Madagascar to Fiji, most Indo-Malesian, few Australia.
Evolution. Plant-Animal Interactions. Caterpillars of the tortricid Phricanthini moths are known only from Dilleniaceae (Powell et al. 1999).
Pollination Biology & Seed Dispersal. Buzz pollination is likely to be common in Dilleniaceae (Endress 1997b).
The dispersal unit is generally the seed, which may be arillate and then endozoochorous (Dillenia), or myrmecochorous, as in most of the rest of the family (Lengyel et al. 2009, 2010).
Chemistry, Morphology, etc. There are often sclereids in the pith. Hibbertia is very variable both vegetatively and florally. Some species have very much reduced leaves and winged, photosynthetic stems, floral symmetry varies, and stamen number varies from one to well over 150. The monosymmetric flowers of Didesmandra aspera have two bundles of stamens on the functionally upper side of the flower, in each there is a single fertile stamen longer than the rest; the flower is drawn as if the plane of symmetry in horizontal (Stapf 1900); the monosymmetric flowers of Schumacheria have only a single staminal bundle in which all stamens are about the same lengths.
See Kubitzki (1971) and especially Horn (2006, 2009) for general information, Paetow (1931), Sastri (1958) and Swamy and Periasamy (1955) for floral morphology, embryology, etc., and Tucker and Bernhardt (2000) for floral development in Hibbertia.
Phylogeny. For relationships, I follow Horn (2002, 2009). Tetracera has reticulate perforation plates in its smallest vessels and its endotesta seems to be poorly differentiated (Horn 2006); if the latter in particular is confirmed, adjustments to clade characterizations may be in order.
Classification. See Horn (2009).
Synonymy: Delimaceae Martius, Hibbertiaceae J. Agardh, Soramiaceae Martynov