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The families of flowering plants

L. Watson and M.J. Dallwitz

Escalloniaceae Dum.

~ Saxifragaceae or Grossulariaceae in many older works.

Including Polyosmaceae Blume; excluding Abrophyllaceae T. Nakai,, Argophyllaceae, Carpodetaceae, Eremosynaceae, Ixerbaceae, Rousseaceae, Tribelaceae.

Habit and leaf form. Trees and shrubs. ‘Normal’ plants. Plants non-succulent. Mesophytic. Leaves alternate, or opposite, or whorled; ‘herbaceous’, or leathery, or fleshy; petiolate; non-sheathing; not gland-dotted; without marked odour; simple; epulvinate. Lamina entire; pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins crenate, or serrate, or dentate (the teeth mostly gland-tipped). Vegetative buds scaly, or not scaly. Leaf development not ‘graminaceous’.

Leaf anatomy. The leaf lamina dorsiventral. Stomata present (at least sometimes very small with guard-cells almost circular in outline, cf. some Cunoniaceae). Hairs present; eglandular and glandular (at least in Escallonia); unicellular and multicellular. Unicellular hairs simple (pointed, and rather thick walled). Complex hairs present (in Escallonia); peltate and capitate. Adaxial hypodermis present (commonly), or absent. Lamina without secretory cavities. Minor leaf veins without phloem transfer cells (Escallonia).

Axial (stem, wood) anatomy. Pith somewhat spongy or becoming hollow. Secretory cavities absent. Cork cambium present; initially deep-seated, or initially superficial. Nodes unilacunar, or tri-lacunar. Primary vascular tissues in a cylinder, without separate bundles; collateral. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays tending to be mixed wide and narrow.

The wood semi-ring porous, or diffuse porous. The vessels small (typically), or medium to large (in Polyosma). The vessel end-walls scalariform (typically), or reticulately perforated and scalariform. The vessels without vestured pits; with spiral thickening (rarely), or without spiral thickening. The axial xylem with tracheids; without vasicentric tracheids; with fibre tracheids; including septate fibres. The fibres without spiral thickening. The parenchyma apotracheal (diffuse). The secondary phloem not stratified. ‘Included’ phloem absent. The wood not storied.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’. The ultimate inflorescence units cymose, or racemose. Flowers regular; (4–)5(–6) merous; cyclic. Floral receptacle with neither androphore nor gynophore. Free hypanthium present, or absent. Hypogynous disk present.

Perianth with distinct calyx and corolla; (8–)10(–12); 2 whorled; isomerous. Calyx (4–)5(–6); 1 whorled; polysepalous, or gamosepalous; regular; persistent; imbricate, or valvate; with the median member posterior. Corolla (4–)5(–6); 1 whorled; not appendiculate; polypetalous (nearly always), or gamopetalous (rarely, with a short tube). Corolla lobes markedly longer than the tube. Corolla imbricate, or valvate; regular. Petals clawed, or sessile.

Androecium (4–)5(–6), or (8–)10(–12). Androecial members free of the perianth (perigynous); free of one another; 1 whorled, or 2 whorled. Androecium exclusively of fertile stamens (when only one whorl), or including staminodes (when two whorls). Staminodes when present, (4–)5(–6). Stamens (4–)5(–6); isomerous with the perianth; (fertile) oppositisepalous; alternating with the corolla members. Anthers dorsifixed; dehiscing via longitudinal slits; introrse. Pollen shed as single grains. Pollen grains aperturate; 3 aperturate; colporate.

Gynoecium 1–6 carpelled. Carpels reduced in number relative to the perianth (usually), or isomerous with the perianth. The pistil when syncarpous, 1 celled, or 2–6 celled. Gynoecium apocarpous (rarely), or syncarpous; eu-apocarpous (rarely), or semicarpous to eu-syncarpous; superior to inferior. Carpel (when apocarpous) 15–100 ovuled (‘many’). Placentation when apocarpous marginal. Ovary when syncarpous 1 locular, or 2–6 locular. Gynoecium in Escallonia median; stylate. Styles 1–6; apical. Stigmas wet type; non-papillate; Group IV type. Placentation when unilocular parietal; when plurilocular axile. Ovules in the single cavity when unilocular, 15–100 (‘many’); when plurilocular, 15–50 per locule (‘many’); anatropous; unitegmic (Escallonia); tenuinucellate (in Escallonia and Polyosma). Endothelium differentiated. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids elongated. Endosperm formation nuclear.

Fruit fleshy, or non-fleshy; dehiscent, or indehiscent; a capsule, or a berry. Seeds copiously endospermic.

Physiology, phytochemistry. Sugars transported as sugar alcohols + oligosaccharides + sucrose (in Escallonia, but depauperate in oligosaccharides). Not cyanogenic. Iridoids detected; ‘Route I’ type (normal and seco). Proanthocyanidins present, or absent; when present, cyanidin, or delphinidin. Flavonols present; kaempferol, or quercetin, or kaempferol and quercetin (mostly both). Ellagic acid absent (6 species, 3 genera). Aluminium accumulation demonstrated (rarely), or not found.

Geography, cytology. Temperate to tropical. Tropical and South temperate, mostly South America and Australasia.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Corniflorae; Cornales. Cronquist’s Subclass Rosidae; Rosales. APG III core angiosperms; core eudicot; Superorder Asteranae; campanulid. APG IV Order Escalloniales.

Species about 140. Genera 7; Anopterus, Cuttsia, Escallonia, Forgesia, Polyosma, Valdivia.

General remarks. Escalloniaceae are one of a few families that have long posed major difficulties of assignment, not only between (for example) Dahlgren’s Araliiflorae and Corniflorae, but also in terms of the higher level groupings Crassinucelli and Tenuinucelli, which evidently represent a major divergence in the Dicot line of descent (cf.Young and Watson 1970, Chase et al. 1993). Molecular sequencing studies place most of them firmly in the Tenuinucelli, but different components appear in association with three of the major linages perceived therein (Backlund and Bremer, 1997). Adjustments to the present package await comprehensive reassignments, along with preparation of the requisite revised family descriptions; and if this attempt to compile a sensu stricto description of Escalloniaceae under-estimates variation, the taxonomic worth of segregate families (see above) will need to be re-assessed.

Illustrations. • Le Maout and Decaisne: Escallonia. • Escallonia illinita: Bot. Reg. 1900 (1836). • Escallonia montevidensis: Bot. Reg. 1467, 1831. • Escallonia polifolia: Hook. Ic. Pl. 2 (1837). • Escallonia rosea, as E. pterocladon: Bot. Mag. 81 (1855). • Polyosma hookeri: Hook. Ic. Pl. 23 (1894).

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 5th March 2018.’.