EXTANT SEED PLANTS

Plant woody, evergreen; nicotinic acid metabolised to trigonelline, (cyanogenesis via tyrosine pathway); primary cell walls rich in xyloglucans and/or glucomannans, 25-30% pectin [Type I walls]; lignins rich in guaiacyl units; true roots present, apex multicellular, xylem exarch, branching endogenous; arbuscular mycorrhizae +; shoot apical meristem multicellular, interface specific plasmodesmatal network; stem with ectophloic eustele, endodermis 0, xylem endarch, branching exogenous; vascular tissue in t.s. discontinuous by interfascicular regions; vascular cambium + [xylem ("wood") differentiating internally, phloem externally]; wood homoxylous, tracheids +; 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 in 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 sharply 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 , 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.

Evolution. Possible apomorphies for flowering plants are in bold. Note that the actual level to which many of these features, particularly the more cryptic ones, should be assigned is unclear, 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. For example, if reticulate-perforate pollen is optimized to the next node on the tree (see Friis et al. 2009 for a discussion), it effectively makes the pollen morphology of the common ancestor of all angiosperms ambiguous....

NYMPHAEALES [AUSTROBAILEYALES [[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]]]]: vessels +, elements with scalariform perforation plates, axial parenchyma diffuse or diffuse-in-aggregate; tectum reticulate-perforate [here?]; ?genome duplication; "DEAER" motif in AP3 and PI genes lost, gaps in these genes.

ERICALES [ASTERID I + II]:ovules tenuinucellate.

ASTERID I + II: ellagic acid 0, proanthocyanidins not common; inflorescence cymose; C forming a distinct tube; A epipetalous, = and opposite sepals or P [polyandry (secondary) very uncommon indeed].

ASTERID II: Myricetin 0; vessel elements with scalariform perforation plates; flowers rather small, style short; endosperm copious, embryo short/very short.

ASTERALES [ESCALLONIALES [BRUNIALES [APIALES [PARACRYPHIALES + DIPSACALES]]]]: iridoids +; inflorescence?; C tube initiation early; G [2-3], inferior.

ESCALLONIALES [BRUNIALES [APIALES [PARACRYPHIALES + DIPSACALES]]]: ?

ESCALLONIALES Doweld  Main Tree, Synapomorphies.

Inflorescence racemose; petals free, anthers basifixed, nectary ["disc"] +, integument 5-10 cells across, style long. - 1 family, 9 genera, 130 species.

Includes Escalloniaceae.

Synonymy: Tribelales Doweld - Escallonianae Doweld

ESCALLONIACEAE Dumortier, nom. cons.   Back to Escalloniales

Plants Al accumulators; inflorescence racemose, style long.

9[list] /130. Réunion, E. Himalayas and S. China to E. Australia and New Zealand, Central and South America.

Polyosma

Trees; iridoids +; storying +; pericycle sclereidal; nodes 1:1; petiole bundle?; stomata ?; hairs unicellular; leaves opposite, margins toothed or not; inflorescence a raceme; flowers 4-merous; K connate, C valvate, free, pollen triporate; G [2], inferior, placentation intruding parietal, many ovules/carpel, integument to 10 cells across, ?endothelium, stigma capitate, bilobed; fruit a 1-seeded drupe; seed coat to 10 cells thick; endosperm thick-walled, starchy, embryo undifferentiated; n = ?

1/60. E. Himalayas and S. China to E. Australia and New Caledonia (map: in part from GBIF Data Portal, www.gbif.net, 3.1.2009).

Escallonia, etc.

(Acaulescent) shrubs to trees (annual herbs); route I seco- and route II decarboxylated iridoids, flavonols +; (cork cambium deep-seated - Escallonia); nodes 3:3 (1:1, 5:5); petiole bundle arcuate; cells in heads of gland hairs radially arranged; stomata anomocytic; leaves spiral, supervolute (conduplicate), margins with broad glandular teeth and two accessory veins (entire); (inflorescence a cyme - Eremosyne; flowers single, terminal - Tribeles); flowers 5-9-merous, C contorted, (± connate - Escallonia), anthers longer than connective (short - Tribeles), placentoid +; G [2-4], (largely superior), transverse, or median member adaxial, placentation also basal, parietal, 1 ascending-many (bitegmic - Tribeles) ovules/carpel, endothelium weak, integument 5-8 cells across, embryo sac protruding at micropyle, style ± divided or not, stigma punctate to capitate or clavate-lobed, wet; fruit a septicidal capsule, often splitting down the sides (indehiscent); exotestal cells with inner walls thickened and lignified (not), elongated or not (palisade - Tribeles), meso- and/or endotesta usu. persist; micropylar haustoria +, (embryo long); n = 12.

8/68: Escallonia (40: stipular prickles occasional). Scattered, but largely southern: Central and South America, SE and SW Australia (Eremosyne pectinata), New Zealand, Réunion (map: from Sleumer 1968). [Photos - Escallonia Flower, Valdivia Flower]

Chemistry, Morphology, etc. This is a very heterogeneous group. Eremosyne is an annual herb that has leaves with more or less lobed margins and palmate-acrodromous venation, a cymose inflorescence, small flowers with a valvate calyx, pollen with incomplete tectum and complex endaperture, and a largely superior bicarpellate gynoecium with 1 ascending ovule/carpel and two largely separate styles. Its fruit is a capsule. Tribeles australis is a small, prostrate shrub with spirally-arranged leaves that have broad bases and three small teeth at the apex. The small, terminal flowers have a contorted corolla, extrorse anthers, and a style with a three-lobed, subclavate stigma. The shiny seeds long remain attached to the columella of the capsule. The pollen has interrupted muri. Other genera include shrubs to trees, etc.

Forgesia has sclereids alone in the pericyclic sheath. Anopterus has parietal placentation and winged seeds; the exotestal cells are elongated, with thickened inner walls. Escallonia lacks the mitochondrial coxII.i3 intron; other taxa have not been sampled.

The group is very poorly known; there is no information on endosperm development, etc. As Bensel and Palser (1975d, p. 693, see also 1975c) noted of Escallonioideae (note, also including Quintinia [= Pararyphiaceae-Paracryphiales]), "The only conclusion that can be drawn about Escallonioideae is that it has been too little investigated in all aspects" - a conclusion that so far has unfortunately stood the test of time.

For general anatomy, see Gornall et al. (1998), for some information on ovules, see Mauritzon (1933). For anatomy of Forgesia (young stem with a complete vascular cylinder), see Ramamonjiarisoa (1980), and of Escallonia, see Stern (1974), nodal anatomy, see Swamy (1954), indumentum, Al-Shammary and Gornal (1994), and for its seed anatomy, see Krach (1976) and Nemirovich-Danchenko and Lobova (1998), for flowers, Ronse Decraene et al. (2000), for floral orientation, Schnizlein (1843-1870: fam. 170). Much general information is taken from Lundberg (2001c: Polyosmaceae, 2001d: Escalloniaceae), while for information on embryology and seed, see Danilova (1996).

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); an association of Tribelaceae with them is only weakly supported (rbcL alone analysed - Savolainen et al. 2000b). However, a three-gene Bayesian analysis suggested that Escalloniaceae were 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 expanded Escalloniaceae (Lundberg 2001e). However, relationships among the genera remain unclear (Tank, pers. comm). I am grateful to F. Zapata for discussion.

Classification. Lundberg (pers. comm.) suggested combining all these families into one, and so they are (see also A.P.G. 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 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.

Synonymy: Anopteraceae Doweld, Eremosynaceae Dandy, Tribelaceae Airy Shaw