The families of flowering plants
Habit and leaf form. Bitter trees, or shrubs. Leaves evergreen; small to medium-sized; opposite; simple. Lamina entire; conspicuously asymmetric; cross-venulate. Leaves exstipulate. Lamina margins entire, or dentate.
Leaf anatomy. The leaf lamina dorsiventral. Stomata present; mainly confined to one surface (abaxial); anomocytic. Hairs present (on the lower surface); exclusively eglandular; unicellular. Unicellular hairs simple (adpressed). Complex hairs absent. Adaxial hypodermis present. The mesophyll containing crystals. The crystals druses.
Axial (stem, wood) anatomy. Cork cambium present; initially deep-seated (with a succcession of phellogens outside the phloem). Nodes with one trace. Primary vascular tissues probably collateral. Secondary thickening probably developing from a conventional cambial ring. Primary medullary rays narrow (uniseriate).
The vessels small. The vessel end-walls oblique; scalariform. The axial xylem with tracheids; with fibre tracheids. The parenchyma scantily developed.
Reproductive type, pollination. Plants hermaphrodite.
Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in inflorescences; when aggregated, in cymes (these few flowered). The ultimate inflorescence units cymose. Inflorescences terminal. Flowers two bracteolate; somewhat irregular; somewhat zygomorphic; cyclic; tetracyclic. Free hypanthium present.
Perianth with distinct calyx and corolla; (8–)10(–16); 2 whorled; isomerous. Calyx (4–)5(–8); 1 whorled; somewhat gamosepalous, or polysepalous; persistent; slightly imbricate, or valvate; with the median member anterior. Corolla (4–)5(–8); 1 whorled; gamopetalous. Corolla lobes markedly longer than the tube (the tube very short). Corolla imbricate; almost rotate; sub-irregular; yellow.
Androecium 2. Androecial members adnate (attached near the base of the corolla); markedly unequal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 2; reduced in number relative to the adjacent perianth; oppositisepalous (alternate with the posterior and lateral lobes); alternating with the corolla members; filantherous (with short, stout filaments). Anthers connivent; with a broad connective; dehiscing via longitudinal slits; bilocular (large, the pollen sacs undulately plicate and twisted). Pollen grains aperturate; 3 aperturate; colporate.
Gynoecium 2 carpelled. Carpels reduced in number relative to the perianth. The pistil 1(–2) celled. Gynoecium syncarpous; eu-syncarpous; inferior. Ovary 1 locular (incompletely partitioned). Gynoecium median. Epigynous disk absent. Gynoecium stylate. Styles 1 (short, thick); apical. Stigmas 2 lobed, or 4 lobed (broad). Placentation parietal (the the intruded placentas almost meeting, constituting partial partitions). Ovules in the single cavity 20–50 (many); ascending; anatropous; unitegmic; tenuinucellate.
Fruit non-fleshy; dehiscent; a capsule. Capsules septicidal and valvular. Seeds copiously endospermic. Embryo well differentiated (though small). Cotyledons 2. Embryo straight.
Physiology, phytochemistry. Not cyanogenic. Iridoids not detected. Proanthocyanidins absent. Aluminium accumulation not found.
Geography, cytology. Neotropical. Tropical. Northwestern South America.
Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgrens Superorder Corniflorae; Dipsacales (re-assigned). Cronquists Subclass Rosidae; Rosales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; campanulid; Order Bruniales.
Species 8. Genera 1; only genus, Columellia.
Illustrations. • Columellia obovata: Hutchinson. • Columellia oblonga: Curtis, B. Mag. 101 (1875). • Le Maout and Decaisne: Columellia.
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: 24th October 2017. delta-intkey.com/angio’.