LIGNOPHYTA
Plant a shrub or tree; true roots +, origin endogeneous, root cap +, apex multicellular; endodermis +; shoot apical meristem multicellular; lateral meristems +, cork cambium producing cork abaxially, vascular cambium producing phloem abaxially and xylem adaxially; lamina with mean venation density 1.8 mm/mm2 (to 5 mm/mm2).
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, so no Maüle reaction; root xylem exarch, cork cambium deep seated; arbuscular mycorrhizae +; shoot apical meristem interface specific plasmodesmatal network; stem with vascular tissue around central pith [eustele], vascular bundles with interfascicular tissue, ectophloic, endodermis 0, xylem endarch; 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; branches exogenous; leaves with single trace from vascular sympodium ["nodes 1:1"]; vascular bundles collateral [stem: phloem external; leaf: phloem abaxial]; stomata morphology?, pore opening controlled by abscisic acid; leaves with petiole and lamina, spiral, development basipetal, blade simple; axillary buds +, not associated with all leaves; 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 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, flagellae numerous; ovules increasing considerably in size between pollination and fertilization, 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, embryo straight, shoot and root at opposite ends [allorrhizic], white, cotyledons 2; plastid transmission maternal; ycf2 gene in inverted repeat, 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, 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 unilacunar [1:?]; stomata brachyparacytic [ends of subsidiary cells level with ends of pore], outer stomatal ledges producing vestibule; lamina formed from the primordial leaf apex, margins toothed, development of venation acropetal, secondary veins pinnate, overall growth ± diffuse, venation hierarchical, fine venation reticulate, 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 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, 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 columellar, endexine thin, compact, lamellate only in the apertural regions; nectary 0; G 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, 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]; ovule not increasing in size between pollination and fertilization; pollen binucleate at dispersal, male gametophyte trinucleate, germinating in less than 3 hours, pollination siphonogamous, tube elongated, growing between cells, growth rate 20-20,000 µm/hour, outer wall pectic, inner wall callose, 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, becoming much larger than ovule at time of fertilization; endosperm diploid, cellular [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; embryogenesis cellular; germination hypogeal, seedlings/young plants sympodial; Arabidopsis-type telomeres [(TTTAGGG)n]; 2C genome size 1-8.2 pg [1 pg = 109 base pairs], 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]].
[NYMPHAEALES [AUSTROBAILEYALES [[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]]]]]: vessels +, elements with elongated scalariform perforation plates; 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]]]]: essential oils in specialized cells [lamina and P ± pellucid-punctate]; tension wood 0; 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 +; 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 positiion]; embryo sac bipolar, 8 nucleate, antipodal cells persisting; endosperm triploid; ?germination.
[MONOCOTS [CERATOPHYLLALES + EUDICOTS]]: (veins in lamina often 7-17mm/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 scattered, asarone 0 [unknown in some groups, + in some asterids]; root epidermis derived from root cap [?Buxaceae, etc.]; 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?; 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 developing internally/adaxially to the corolla whorl and successively alternating, (numerous, but then usually fasciculate and/or centrifugal); pollen tricolporate; G [5], G [3] 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.
[SANTALALES [BERBERIDOPSIDALES [CARYOPHYLLALES + ASTERIDS]]] / ASTERIDS ET AL. / SUPERASTERIDS : ?
[BERBERIDOPSIDALES [CARYOPHYLLALES + ASTERIDS]]: ?
[CARYOPHYLLALES + ASTERIDS]: seed exotestal; embryo long.
ASTERIDS / Sympetalae redux? / ASTERIDAE / ASTERANAE Takhtajan: nicotinic acid metabolised to its arabinosides; (iridoids +); tension wood decidedly uncommon; C enclosing A and G in bud, (connate, if evident only early in development and then petals often appearing to be free); anthers dorsifixed?; (nectary gynoecial); style +, long; ovules unitegmic, integument thick, endothelium +, nucellar epidermis does not persist; exotestal cells lignified, esp. on anticlinal and/or inner periclinal walls; endosperm cellular.
[ERICALES [ASTERID I + ASTERID II]]: (ovules lacking parietal tissue) [tenuinucellate].
[ASTERID I + ASTERID II] / CORE ASTERIDS: ellagic acid 0, non-hydrolysable tannins not common; sugar transport in phloem active; inflorescence basically cymose; A = and opposite sepals or P, (numerous, usu. associated with increased numbers of C or G); (pollen with orbicules); style short[?]; duplication of the PI gene.
ASTERID II / CAMPANULIDAE: myricetin 0; vessel elements with scalariform perforation plates; flowers rather small; endosperm copious, embryo short/very short.
[ASTERALES [ESCALLONIALES [BRUNIALES [APIALES [PARACRYPHIALES + DIPSACALES]]]]] / APIIDAE: iridoids +; C forming a distinct tube, tube initiation early; A epipetalous; G inferior, [2-3], style long[?].
[ESCALLONIALES [BRUNIALES [APIALES [PARACRYPHIALES + DIPSACALES]]]]: ?
Evolution. Divergence & Distribution. The appproximate age for this clade is (106-)96(-85) m.y., diversification probably occurring in the southern hemisphere (Beaulieu et al. 2013).
Phylogeny. Various small families have been placed here or elsewhere in the asterid II clade, but with uncertain support; recent work is clarifying their relationships (Winkworth et al. 2008a), especially that of Tank and Donoghue (2010). For Polyosmaceae and Escalloniaceae, see below. Paracryphiaceae, Quintiniaceae and Sphenostemonaceae are combined as Paracryphiaceae and form a clade sister to Dipsacales, thus the clade [Paracryphia + Quintinia] (Paracryphiaceae) was sister to Dipsacales, although not in analyses that included coding chloroplast genes (Winkworth et al. 2008a).
In earlier versions of this site (pre April 2008), [Columelliaceae + Desfontainiaceae] (= Columelliaceae s.l.) were placed sister to Dipsacales, with which they show some morphological similarities. The position of Columelliaceae s.l. in or near Dipsacales had been suggested by Bremer et al. (2001) and especially by Lundberg (2001e; see also Backlund 1996), although support was at best moderate. Both Columelliaceae s.l. and Dipsacales all have opposite leaves, and Columellia has amoeboid tapetum (c.f. Bremer et al. 2001) like Dipsacales although Desfontainia does not (Maldonado de Magnano 1986a). If the pair are not immediately related to Dipsacales, as now seems probable, the similarities that they have with Dipsacales may indicate either substantial homoplasy or a suite of lower-level synapomorphies in the asterid II group of which there is currently no indication and which is less likely. Other relationships have been suggested (Gustafsson et al. 1996; Backlund & Bremer 1997; Pyck & Smets 2000; Bell et al. 2001); for the possible association of Bruniaceae with Asterales, see Lundberg (2001e). Here Columelliaceae s.l. together with Bruniaceae make up Bruniales.
For relationships of the larger families, see the asterid IIclade. The overall topology [Bruniales [Apiales [Paracryphiales + Dipsacales]]] seem to be fairly well established (Winkworth et al. 2008a; Tank & Donoghue 2010; Beaulieu et al. 2013); however, the position of Escalloniales is sometimes rather poorly supported.
ESCALLONIALES Martius Main Tree, Synapomorphies.
Inflorescence racemose; petals free; A adnate or not to C, anthers basifixed; nectary +; ovule with integument 5-10 cells across. - 1 family, 9 genera, 130 species.
Note: Possible apomorphies are now being added throughout the site; they 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 because there is very considerable homoplasy for many characters, with with variation within and between clades. Furthermore, basic information for all too many characters is very incomplete, often 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...
Evolution. Divergence & Distribution. Magallón and Castillo (2009: but note topology) offer estimates of ca 97 m.y. for the age the stem group.
Includes Escalloniaceae.
Synonymy: Escalloniineae Shipunov - Tribelales Doweld
ESCALLONIACEAE Dumortier, nom. cons. Back to Escalloniales
Plants Al accumulators; inflorescence racemose; G inferior; 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 Blume
Trees; iridoids +; wood storying +; pericycle with sclereids; nodes 1:1; petiole bundle?; stomata ?; hairs unicellular; leaves opposite, lamina margins toothed or not; flowers 4-merous; K connate, C valvate; pollen triporate; G placentation intrusive 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; endosperm starchy, thick-walled, ?haustoria, embryo undifferentiated; n = ?
1/60. E. Himalayas and S. China to E. Australia and New Caledonia (map: in part from GBIF Data Portal 3.1.2009).
Synoymy: Polyosmaceae Blume
Escallonia, etc.
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; heads of glandular hairs with radially arranged cells; 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 +; ?pollen; G [2-4], (largely superior), collateral, or median member adaxial, placentation also basal, 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, (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 endosperm haustoria +, (embryo long); n = 12.
8/68: Escallonia (40). Scattered, but largely southern: Central and South America, SE and SW Australia (Eremosyne pectinata), New Zealand, Réunion (map: from Sleumer 1968; FloraBase 2007). [Photos - Escallonia Flower, Valdivia Flower.]
Synonymy: Anopteraceae Doweld, Eremosynaceae Dandy, Tribelaceae Airy Shaw
Chemistry, Morphology, etc. This is a very heterogeneous and poorly known group; 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 [= 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.
Forgesia has sclereids alone in the pericyclic sheath. Escallonia occasionally has prickles in the stipular position. Anopterus has parietal placentation, apparently a long micropyle, and winged seeds; the exotestal cells are elongated, and have thickened inner walls. Escallonia lacks the mitochondrial coxII.i3 intron; other taxa have not been sampled.
For general anatomy, see Gornall et al. (1998), for some information on ovules, see Mauritzon (1933). For anatomy of Forgesia, see Ramamonjiarisoa (1980: young stem with a complete vascular cylinder). For Escallonia, see Stern (1974: anatomy), Swamy (1954: nodes), Al-Shammary and Gornal (1994: indumentum), and Krach (1976) and Nemirovich-Danchenko and Lobova (1998), both seeds, and Schnizlein (1843-1870: fam. 170: floral orientation). Much general information is taken from Lundberg (2001c: Polyosmaceae, 2001d: Escalloniaceae), while for information on embryology and seed, see Danilova (1996), and for 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); 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); details of relationships between the genera remain unclear (Tank & Donoghue 2010, see also Beaulieu et al. 2013, but sampling). In a 17-gene analysis by Soltis et al. (2011), Polyosma linked with Quintinia (Paracryphiales here, q.v. for a possible explanation). For phylogenetic relationships within Escallonia, see Zapata (2013).
Classification. Lundberg (pers. comm.) thought that all these families should be combined 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 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.
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