LIGNOPHYTA

True roots +; lateral meristems: cork cambium producing cork abaxially, vascular cambium producing phloem abaxially and xylem adaxially.

EXTANT SEED PLANTS/SPERMATOPHYTA

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 derived from (some) sinapyl and particularly coniferyl alcohols, thus containing p-hydroxyphenyl and guaiacyl lignin units, (lignins derived from p-coumaryl alcohol, i.e. S [syringyl] lignin units); true roots present, apex multicellular, xylem exarch, and 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 and rays alone, tracheid/tracheid pits circular, bordered; mature sieve tube/cell lacking functioning nucleus, plastids with starch grains; phloem fibres +; stem cork cambium superficial, root cork cambium deep seated; leaves with single trace from sympodium ["nodes 1:1"]; stomata ?; leaf vascular bundles collateral; leaves megaphyllous [determinancy evolved first, then ad/abaxial symmetry], spiral, simple, lamina with vein density up to 5 mm/mm² [mean for all non-angiosperms 1.8]; axillary buds associated with at most some leaves; prophylls [including bracteoles] two, lateral; 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, developing after pollination, 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 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.

MAGNOLIOPHYTA

Lignans, O-methyl flavonols, dihydroflavonols, triterpenoid oleanane, non-hydrolysable tannins, quercetin and/or kaempferol +, 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; shoot apex with tunica-corpus construction, tunica 2-layered; reaction wood ?, with gelatinous fibres; 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 cells from same mother cell that gave rise to the sieve tube; sugar transport in phloem passive; nodes unilacunar [1:?]; stomata with ends of guard cells level with pore, paracytic, outer stomatal ledges producing vestibule; leaves petiolate, lamina [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; most/all leaves with axillary buds; flowers perfect, pedicellate, polysymmetric, parts spiral [esp. the A], free, numbers unstable, development in general centripetal; P not sharply differentiated, with a single trace, outer members not enclosing the rest of the bud, often smaller than inner members; 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 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, tectum continuous or microperforate, ektexine columellar, endexine thin, compact, lamellate only in the apertural regions; nectary 0; G free, several, ascidiate, with postgenital occlusion by secretion, stylulus short, hollow, cavity not lined by distinct epidermal layer, stigma ± decurrent, 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, megaspore tetrad linear, functional megaspore chalazal, lacking sporopollenin and cuticle; female gametophyte four-celled [one module, nucleus of egg cell sister to one of the polar nuclei]; P deciduous in fruit; seed exotestal; pollen binucleate at dispersal, trinucleate eventually, germinating in less than 3 hours, pollination siphonogamous, tube elongated, growing at 80-600 µm/hour, with pectic outer wall, callose inner wall and callose plugs, growing between cells, penetration of ovules via micropyle [porogamous] within ca 18 hours, distance to first ovule 1.1.-2.1 mm, tube moves between nucellar cells; double fertilisation +, endosperm diploid, cellular [micropylar and chalazal domains develop diffently, 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 cellular ab initio, minute; germination hypogeal, seedlings/young plants sympodial; Arabidopsis-type telomeres [(TTTAGGG)_n]; whole genome duplication, 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]].

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

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

ESCALLONIALES Martius  Main Tree, Synapomorphies.

Inflorescence racemose; petals free; anthers basifixed; nectary +; ovule with integument 5-10 cells across. - 1 family, 9 genera, 130 species.

Evolution. Divergence & Distribution. Magallón and Castillo (2009) offer estimates of ca 96.8 and 97.2 million years for relaxed and constrained penalized likelihood datings respectively for the stem group - but note topology, probably an overestimate.

Includes Escalloniaceae.

Synonymy: Escalloniineae Shipunov - Tribelales Doweld

ESCALLONIACEAE Dumortier, nom. cons.   Back to Escalloniales

Plants Al accumulators; inflorescence racemose; style long; parietal tissue ca 1 cell across[?].

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, lamina margins toothed or not; inflorescence a raceme; flowers 4-merous; K connate, C valvate, free; pollen triporate; G [2], inferior, placentation intruding parietal, stigma capitate, bilobed; ovules many/carpel, integument to 10 cells across, ?endothelium, parietal tissue ca 1 cell across[?], nucellus base massive; (megaspore mother cells several); 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).

Synoymy: Polyosmaceae Blume

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, lamina vernation 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, style ± divided or not, stigma punctate to capitate or clavate-lobed, wet; ovule 1-many/carpel, (ascending), integument 5-8 cells across, micropyle long, (ovule bitegmic - Tribeles), endothelium +/weak; embryo sac protruding at micropyle; fruit a septicidal capsule, often splitting down the sides; 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.]

Synonymy: Anopteraceae Doweld, Eremosynaceae Dandy, Tribelaceae Airy Shaw

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, apparently a long micropyle, 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 (for them, 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) and a summary of information on Eremosyne (?ovules not quite tenuinucellate), see Hibsch-Jetter et al. (1997).

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, most relationships between the genera remain unclear (Tank & Donoghue 2010).

Interestingly, in a 17-gene analysis by Soltis et al. (2011), Polyosma linked with Quintinia (Paracryphiales here). Support for this position came from the mitochondrial component of the analysis, and after careful examination of the problem, Soltis et al. (2011) were inclined to think that horizontal gene transfer of the mitochondrial genes might be involved.

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.

Thanks. I am grateful to F. Zapata for discussion.