EXTANT SEED PLANTS

Plant woody, evergreen; nicotinic acid metabolised to trigonelline; primary cell walls rich in xyloglucans and/or glucomannans, 25-30% pectin [Type I walls]; lignins rich in guaiacyl units; true roots present, apex multicellular, xylem exarch, branching endogenous; arbuscular mycorrhizae +; shoot apical meristem multicellular; stem with ectophloic eustele, endodermis 0, xylem endarch, branching exogenous; vascular tissue in t.s. discontinuous by interfascicular regions; vascular cambium + [xylem ("wood") differentiating internally, phloem externally]; wood homoxylous, tracheids +; tracheid/tracheid pits circular, bordered; sieve tube/cell plastids with starch grains; phloem fibers +; stem cork cambium superficial, root cork cambium deep seated; nodes ?; stomata ?; leaf vascular bundles collateral; leaves spiral, simple, axillary buds?, prophylls [including bracteoles] two, lateral, veins -5 mm/mm² [mean for all non-angiosperms 1.8]; plant heterosporous, sporangia eusporangiate, on sporophylls, sporophylls aggregated in indeterminate cones/strobili; true pollen [microspores, i.e. no distal pore for release of gametes] +, grains mono[ana]sulcate, exine and intine homogeneous, ovules unitegmic, crassinucellate, megaspore tetrad tetrahedral, only one megaspore develops, megasporangium indehiscent; male gametophyte development first endo- then exosporic, tube developing from distal end of grain, to ca 2 mm from receptive surface to egg, gametes two, with cell walls, with many flagellae; female gametophyte endosporic, initially syncytial, walls then surrounding individual nuclei; seeds "large", first cell wall of zygote transverse, embryo straight, endoscopic [suspensor +], short-minute, with morphological dormancy, white, cotyledons 2; plastid transmission maternal; two copies of LEAFY gene, PHY gene duplication [N/O//A/C and P//BE lines], mitochondrial nad1 intron 2 and coxIIi3 intron present.

MAGNOLIOPHYTA

Plant woody, evergreen; lignans, O-methyl flavonols, dihydroflavonols, triterpenoid oleanane, non-hydrolysable tannins, quercetin and/or kaempferol +, apigenin and/or luteolin scattered, cyanogenesis via tyrosine pathway [ANITA grade?], lignins derived from both coniferyl and sinapyl alcohols, containing syringaldehyde [in positive Maüle reaction, syringyl:guaiacyl ratio less than 2-2.5:1], and hemicelluloses as xyloglucans; root apical meristem intermediate-open; root vascular tissue oligarch [di- to pentarch], lateral roots arise opposite or immediately to the side of [when diarch] xylem poles; origin of epidermis with no clear pattern [probably from inner layer of root cap], trichoblasts [differentiated root hair-forming cells] 0; stem with 2-layered tunica-corpus construction; wood fibers and wood parenchyma +; reaction wood ?, with gelatinous fibres; starch grains simple; primary cell wall mostly with pectic polysaccharides; tracheids +; sieve tubes eunucleate, with a sieve plate and cytoplasm with P-proteins, companion cells from same mother cell that gave rise to the sieve tube; nodes unilacunar [1:?]; stomata with ends of guard cells level with pore, paracytic, outer stomatal ledges producing vestibule; leaves with petiole and lamina [the latter formed from the primordial leaf apex], development of venation acropetal, 2ndary veins pinnate, fine venation reticulate, veins (1.7-)4.1(-5.7) mm/mm², endings free; flowers perfect, polysymmetric, parts spiral [esp. the A], free, development in general centripetal, numbers unstable, P not differentiated, outer members not enclosing the rest of the bud, smaller than inner members, A many, with a single trace, introrse, filaments stout, anther ± embedded in the filament, tetrasporangiate, dithecal, with at least outer secondary parietal cells dividing, each theca dehiscing longitudinally by action of hypodermal endothecium, endothecial cells elongated at right angles to long axis of anther, tapetum glandular, binucleate, microspore mother cells in a block, microsporogenesis successive, walls developing by centripetal furrowing, pollen subspherical, binucleate at dispersal, trinucleate eventually, tectum continuous or microperforate, ektexine columellar, endexine thin, compact, lamellate only in the apertural regions, pollen germinating in less than 3 hours, tube elongated, growing at 80-600 µm/hour, with callose plugs and callose-based walls, penetrating between cells, siphonogamy, penetration of ovules within ca 18 hours, distance to first ovule 1.1.-2.1 mm, nectary 0, G free, several, ascidiate, with postgenital occlusion by secretion, few [?1] ovules/carpel, ovules marginal, anatropous, bitegmic, [outer integument often largely subdermal in origin, inner integument dermal], micropyle endostomal, integuments 2-3 cells thick, megasporocyte single, megaspore lacking sporopollenin and cuticle, chalazal, female gametophyte four-celled [one-modular, nucleus of egg cell sister to one of the polar nuclei], stylulus short, hollow, stigma ± decurrent, dry [not secretory]; P deciduous in fruit; seed exotestal; double fertilisation +, endosperm diploid, cellular [first division oblique, micropylar end initially with a single large cell, chalazal end more actively dividing], copious, oily and/or proteinaceous, embryo cellular ab initio, minute; germination hypogeal, seedlings/young plants sympodial; Arabidopsis-type telomeres [(TTTAGGG)_n]; whole genome duplication, single copy of LEAFY and RPB2 gene, knox genes extensively duplicated [A1-A4], AP1/FUL gene, paleo AP3 and PI genes [paralogous B-class genes] +, with "DEAER" motif, SEP3/LOFSEP and PHYA + C/PHYB + E gene pairs.

Possible apomorphies are in bold. Note that the actual level to which many of these features, particularly the more cryptic ones, should be assigned is unclear, because some taxa basal to the [magnoliid + monocot + eudicot] group have been surprisingly little studied, there is considerable variation between families in particular for several of these characters, and also because details of relationships among gymnosperms will affect the level at which some of these characters are pegged.

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

In Versions 9 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. Flowers of many core eudicots are indeed very distinctive, as indicated by the characterisation of this clade. Sepals usually have three traces and petals have one, although there is considerable discussion as to the distinction between and evolution of sepals and petals (see Ronse de Craene 2008 and references). It has been suggested that petals in core eudicots are generally derived from tepals, perhaps ultimately bracts, not from stamens (with some exceptions, as in Caryophyllaceae, etc.: Ronse de Craene 2007, 2008). Compared to many eudicots in clades basal to this node, the two perianth whorls are distinctive in that members of each encircle the floral axis, members of the androecial whorls being adaxial/interior to the the inner whorl and not directly associated (except by vasculature) with members of the outer perianth whorl. Taxa that have flowers with many stamens are scattered throughout the core eudicots. A number of these taxa initially have only five or ten primordia, in the former case, the primordia usually arise opposite the petals, rather than alternating with them. Numerous individual stamens then develop from these few initial primordia, and development is often centrifugal (cf. 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). Note, however, that there may be considerable variation in staminal development between closely related multistaminate taxa (e.g. Hufford 1990; Ge et al. 2007). Polyandry is much less common in the asterid I + II clade (q.v. for discussion) and it often appears to be of a rather different nature there. Tentatively, then, and based entirely on gross morphology, there seem to have been major changes in basic floral organisation at the [monocot [Ceratophyllales + eudicot]] node, the [rosids et al. + asterids et al.] node, and the [asterid I + asterid II] node. Note that although Gunnerales are included in core eudicots, the floral morphology of extant Gunnerales is very different from that of other core eudicots and is more similar to that of eudicots basal to core eudicots.

For the floral development of Berberidopsis corallina, a "link" in the evolution of the flower of core eudicots, see Ronse De Craene (2004, 2007). The link is at best usable as an analogy, since several elements of this floral morphology are probably parallelisms within core eudicots and others even reversals; Berberidospidales are embedded in the clade immediately basal to asterids, relationships being [Santalales [Berberidopsidales [Caryophyllales + asterids]] (e.g. Moore et al. 2008; Wang et al. 2009). Chase (2005) noted that in Santalales some parts, particularly stamens, might have several whorls, and this perhaps suggested that canalisation of floral development was less than in some other core eudicots; whether Santalales really are different in this respect from other core eudicot group remains to be established.

There are quite a number of gene duplications known from this general area, perhaps a whole genome duplication is involved (e.g. Litt & Irish 2003; Kramer et al. 2004; Kim et al. 2004; Zahn et al. 2005b; Howarth & Donoghue 2006; especially Kramer & Zimmer 2006; Shan et al. 2007). Looking more specifically at floral genes, note that not all major core eudicot groups have been sampled for the euAP1 gene, the situation in Santalales, for example, being unknown; there has been another duplication of this gene (and also of the AGL1/2/3 gene) perhaps immediately below this node, but above the Ranunculales node, and the roles these genes may have in many eudicot groups is unknown. However, the eu AP1clade includes key regulators that have been implicated in the specification of perianth identity (Litt & Irish 2003).

Chemistry, Morphology, etc. The occurence of ellagic acid has a distribution similar to that of 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, and what happens in Proteaceae (with axial nectaries, like rosids - see Smets 1988) and Sabiaceae is unfortunately unknown. This gene is not expressed in the extrafloral nectaries of Passifloraceae (Krosnick et al. 2008a). Seed coats with a mechanical layer more than a single cell thick occur throughout BLAs, but again, seed coats of the asterid I + II clade are rather different, usually being only one or two cells across.

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 clade, although the [rosids et al. + asterids et al.] clade is well supported, relationships within it have long been unclear, there being a basal five-radiate polychotomy here before the eighth version of this site. D. Soltis et al. (2003a) in a four-gene analysis suggested that Berberidopsidales are sister to the rest of the core eudicots, but there was only 54% jacknife support for this position. 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 placed sister to Caryophyllales, but with only very moderate support; D. Soltis et al. (2003a) provides rather stronger (83% jacknife) support for this position (see also Soltis et al. 2007a). It also seemed possible that Caryophyllales + Dilleniales and Santalales form 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 recent 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), but again the sampling was only moderate. In a study using the mitochondrial gene matR, Caryophyllales were again 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 the 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 is uncertain, but this was perhaps partly because the ovules of Rhabdodendraceae, there sister to all other Caryophyllales, were interpreted as being unitegmic; recent work suggests 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 cf. Goloboff et al. 2009).

There are, however, major changes afoot. There is some support for placing Crossosomatales as sister to the malvid group (Huerteales, Sapindales, etc.: see Zhu et al. 2007). As we have seen, earlier studies often suggested that Caryophyllales, and perhaps also Santalales and Berberidopsidales, as well as Dilleniales, were closer to the asterids than to any other clade in the polychotomy. In a two-gene study focussing of early-diverging eudicots, all these taxa grouped in a pectinate fashion with the asterids, although support was low (Hilu et al. 2008). In their 12-gene plus plastid inverted repeat study of the rosids, Wang et al. (2009) found Berberidopsidales did not group with rosids, but was sister to a clade made up of the few Caryophyllales and asterids included in the study). Moore et al. (2008) in a preliminary analysis of whole-chloroplast genome data, suggested that most members of the basal polychotomy of the core eudicots could be placed as a series of pectinate branches immediately basal to the asterids (see Santalales). This is consistent with the relationships suggested in the two paragraphs above. The position of Dilleniales remains uncertain, as does the position of Saxifragales and Vitales with respect to rosids; although [Saxifragales, Vitales, rosids] form a strongly-supported clade, it is unclear whether Vitales are sister to Saxifragales or to rosids (Wang et al. 2009). Support for [Vitales + rosids] is only 72% ML bootstrap (Wang et al. 2009).

For further discussion, see Caryophyllales, asterids, Saxifragales, and Vitales - immediately preceding mention of these orders.

ROSIDS ET AL. = DILLENIALES [SAXIFRAGALES [VITALES + ROSIDS]]: nodes 3:3; stipules + [usually apparently inserted on the stem].

DILLENIALES Hutchinson  Main Tree, Synapomorphies.

Secondary veins proceeding straight to the teeth; A many, often centrifugal, G separate, ?micropyle; fruit a follicle; endotesta ± palisade, lignified, exotegmen usu. tracheidal. - 1 family, 10 genera, 300 species.

Some evidence, including seed coat anatomy, suggests a relationship between Dilleniales and Vitales, but relationships between Dilleniales and Caryophyllales have also been suggested (e.g. D. Soltis et al. 2003a; Soltis et al. 2007a). Horne (2006) lists a number of features suggesting a relationship between Dilleniaceae and Rhabdodendraceae, in particular, which was then thought to be sister to the rest of Caryophyllales; some of these could be features (?synapomorphies?) 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.

However, recent work suggests that Rhabdodendraceae are sister to the core Caryophyllales and immediately associated families rather than sister to all Caryophyllales (Drysdale et al. 2007; Brockington et al. 2007). Caryophyllales themselves are sister to asterids (e.g. Hansen et al. 2007; Jansen et al. 2007; Logacheva et al. 2008), while Dilleniales may be associated with the extended rosid clade (see below for details).

From the discussion above, a postion of Vitales as sister to other rosids could be seen as probable (see that page for more details and characters), but, other than that, everything seemed somewhat up in the air until very recently. However, an analysis of all 79 protein-coding plastid genes and four mitochondrial genes suggest that Dilleniales are sister to rosids, although support could be stronger (Moore et al. 2008). Wang et al. (2009: Dilleniales not included) in an analysis of 43,000 bp, largely chloroplast sequences, found substantial resolution within rosids s.l., and the relationships they suggest are followed here (they analysed a twelve gene and inverted repeat data sets separately and combined, preferring ML over MP analyses). Vitales and Saxifragales are successively sister to core rosids ([malvids + fabids]), and can be included in rosids, although the position of the former is only moderately supported (72% bootstrap in a ML analysis).

Includes Dilleniaceae.

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 cylinder; (successive cambia +); cork cambium deep-seated (superficial in Dillenia); (vessel elements with simple perforation plates); true tracheids +; (nodes 1:1 [Hibbertia]); raphides +, also common in wood; epidermis silicified; branching from previous flush; hairs unicellular; leaves spiral, conduplicate, often scabrid, margins toothed (entire), 2ndary veins parallel, teeth with clear glandular expanded apex, base rather broad, stipules 0, or long petiolar flanges [amplexicaul petiole]; inflorescence?; pedicels articulated, (flowers horizontally monosymmetrical); K (3-)5(-20), C (2-)5, often crumpled in bud, A often asymmetrical, (2-)many, from a ring primordium or fasciculate, 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, 1-many (atropous) apotropous often campylotropous ovules/carpel, micropyle zigzag or exostomal, chalaza massive, styluli long, stigmas capitate to punctate, wet (1 record); (fruit a nut; berry), (K enclosing fruit, ± fleshy); funicular aril, often laciniate, exotesta often fleshy (cells large, tanniniferous, becoming flattened - Dillenia), exotegmen tracheidal, with spiral or annular thickenings, endotegmen tanniniferous; n = 4, 5, 8-10, 12, 13; germination phanerocotylar.

10[list]/300: Hibbertia (115, Madagascar to Fiji, but nearly all endemic to Australia), Dillenia (60), Tetracera (40). Tropical and warm temperate (Map: from van Steenis & van Balgooy 1966; van Balgooy 1975; Heywood 1978). [Photos - Collection]

• Dilleniaceae are recognisable by the often strong and parallel secondary veins that proceed straight into the teeth; scalariform tertiary venation is common, and the lamina is often rough; the leaves tend to elongate when they are still rolled up. The bark is often rich brown. The pedicels are articulated near the apex and persist after the flower falls off; the flowers themselves are often conspicuous and have crumpled petals and numerous stamens that are reflexed in bud and often have porose anthers. The fruits are shiny follicles containing arillate seeds; the calyx is persistent, sometimes accrescent, and the filaments are also persistent.

Evolution. The phytophagous tortricid Phricanthini are known only from Dilleniaceae (Powell et al. 1999).

The dispersal unit is generally the seed, which may be arillate and endozoochorous Dillenia or myrmecophilous (most of the rest of the family: Lengyel et al. 2009).

Chemistry, Morphology, etc. Hibbertia, with some 115 species, is very variably both vegetatively and florally. Some taxa have very much reduced leaves and winged, photosynthetic stems, 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 moosymmetric flowers of schumacheria have only a single staminal bundle in which all stamens are about the same lengths. There are often sclereids in the pith.

See Kubitzki (1971) and especially Horn (2006, but 4 subfamilies for 10 genera seems a bit excessive...) for general information.

Phylogeny. Relationships in the family are [Tetracera (lianes) [Doliocarpus, Davilla, etc. (peltate stigma) [Dillenia (amplexicaul petiole) + Hibbertia]]] (Horn 2002). Note that Tetracera has reticulate perforation plates in its smallest vessels, the stomata are paracytic, and the endotesta seems to be in general poorly differentiated (Horn 2006).

Synonymy: Hibbertiaceae J. Agardh, Soramiaceae Martynov