The families of flowering plants
Alternatively Chlaenaceae Thou.
Including Rhodolaenaceae Bullock, Schizochlaenaceae Wetttst.
Habit and leaf form. Beautiful trees, or shrubs; not resinous. Leaves mostly evergreen; alternate; leathery, or herbaceous (?); petiolate (the petioles with complex anatomy, often siphonostelic with medullary bundles); non-sheathing; simple. Lamina entire; pinnately veined; cross-venulate. Leaves stipulate. Stipules often large, intrapetiolar (similar to those in Ficus); free of one another; usually caducous. Lamina margins entire.
Leaf anatomy. The leaf lamina dorsiventral. Stomata present; more or less anomocytic. Hairs present; eglandular and glandular; unicellular, or multicellular. Unicellular hairs branched, or simple. Multicellular hairs branched, or simple. Complex hairs present (often), or absent; peltate, or stellate (commonly). Adaxial hypodermis present, or absent. Lamina without secretory cavities. The mesophyll containing mucilage cells; with sclerenchymatous idioblasts, or without sclerenchymatous idioblasts (usually); containing crystals. The crystals druses.
Axial (stem, wood) anatomy. Young stems with solid internodes. Pith homogeneous, or heterogeneous. Secretory cavities absent (but usually with mucilage cells in pith and cortex). Nodes 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 narrow (exclusively uniseriate).
The wood diffuse porous. The vessels medium; exclusively solitary. The vessel end-walls simple. The vessels with vestured pits (sometimes), or without vestured pits (?); without spiral thickening. The axial xylem with tracheids; without vasicentric tracheids; without fibre tracheids; without septate fibres. The fibres fairly thick walled, without spiral thickening. The parenchyma apotracheal (diffuse). The secondary phloem stratified into hard (fibrous) and soft (parenchymatous) zones. Included phloem absent. The wood not storied.
Reproductive type, pollination. Plants hermaphrodite.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in inflorescences; in cymes, or in umbels, or in panicles. The ultimate inflorescence units cymose. Inflorescences consisting of flowers borne singly or paired within involucres of various forms, in cymose aggregations; with involucral bracts (i.e. the solitary or paired flowers subtended by involucels of bractlets, these distinct or more or less connate, sometimes cupulate and then sometimes interpreted as derived from the pedicel tips). The involucres accrescent (often becoming lignified, surrounding the fruit), or non-accrescent. Flowers regular. Free hypanthium absent. Hypogynous disk present, or absent; extrastaminal; of separate members to annular (more or less cupular, entire or toothed, supposedly staminodial in origin).
Perianth with distinct calyx and corolla; 8(–11); isomerous to anisomerous. Calyx 3(–5); polysepalous (when 5, the two outer members smaller than the three inner, when four either one or three outer members smaller); imbricate. Corolla 5(–6); 1 whorled; polypetalous, or gamopetalous (the petals sometimes very slightly united at the base). Corolla lobes markedly longer than the tube. Corolla contorted.
Androecium 5–10 (Leptolaena), or 12–200 (? usually very numerous). Androecial members branched; usually maturing centrifugally (?); free of the perianth; free of one another, or coherent (sometimes fasciculate, the bundles of filaments weakly connate at the base); when in bundles, 5–10 adelphous. Androecium exclusively of fertile stamens, or including staminodes (the disk sometimes thus interpretable). Staminodes when present, 5–10 (?). Stamens 5–10 (Leptolaena), or 30–200 (? usually very numerous); polystemonous (usually), or isomerous with the perianth to diplostemonous (Leptolaena); filantherous (the filaments slender). Anthers dorsifixed, or basifixed; dehiscing via longitudinal slits; extrorse, or introrse; bilocular; tetrasporangiate. Pollen shed in aggregates; in tetrads. Pollen grains aperturate; 3–6 aperturate; colporate (parasyncolpate).
Gynoecium (1–)3–4(–5) carpelled. Carpels reduced in number relative to the perianth, or isomerous with the perianth, or increased in number relative to the perianth. The pistil 1–5 celled. Gynoecium monomerous (rarely), or syncarpous (usually); of one carpel (rarely), or synstylovarious to eu-syncarpous; superior. Carpel (when monomerous) stylate; apically stigmatic; 1–3 ovuled (?). Ovary when syncarpous (i.e.usually), (1–)3–4(–5) locular. Gynoecium stylate. Styles 1; attenuate from the ovary; apical (usually thick, more or less elongated). Stigmas 1; expanded, usually lobed. Placentation basal to axile, or axile, or axile to apical. Ovules (1–)2–15 per locule (few to several); pendulous to ascending; anatropous.
Fruit non-fleshy. The fruiting carpel when monomerous, indehiscent; an achene, or nucular (?). Fruit dehiscent, or indehiscent; a capsule, or a nut. Capsules when dehiscent, loculicidal. Seeds endospermic (usually, copiously), or non-endospermic (endosperm seldom scanty or wanting). Endosperm not oily (fleshy or horny, starchy). Seeds with starch. Embryo well differentiated. Cotyledons 2 (cordate). Embryo straight.
Physiology, phytochemistry. Aluminium accumulation not found.
Geography, cytology. Paleotropical. Tropical. Madagascar.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgrens Superorder Malviflorae; Malvales. Cronquists Subclass Dilleniidae; Theales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; malvid; Order Malvales.
Species 40. Genera 10; Eremolaena, Leptolaena, Mediusella, Pentachlaena, Perrierodendron, Rhodolaena, Sarcolaena, Schizolaena, Xerochlamys, Xyloölaena.
Illustrations. • Sarcolaena grandiflora, Leptolaena bernieri and L. multiflora: Cavaco in Fl. Madagascar (1952). • Technical details: Leptolaena (Thonner). • Technical details: Leptolaena (Lindley).
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: 13th March 2017. delta-intkey.com/angio’.