The families of flowering plants
Habit and leaf form. Tall trees. Leaves persistent; opposite (usually), or whorled (less often); when whorled 3 per whorl; petiolate; not gland-dotted; simple (rarely), or compound; when compound, unifoliolate, or ternate, or pinnate. Lamina pinnately veined; cross-venulate. Leaves stipulate (and stipellate). Stipules caducous (small). Lamina margins entire, or dentate (sometimes doubly dentate).
Leaf anatomy. The leaf lamina dorsiventral. Extra-floral nectaries absent (commonly), or present. Stomata present; mainly confined to one surface (abaxial); anomocytic. Hairs present (especially abaxially); eglandular; unicellular. Unicellular hairs simple (thick walled, curved). Complex hairs absent. Adaxial hypodermis of one or two layers present. The mesophyll containing crystals. The crystals druses and solitary-prismatic.
Axial (stem, wood) anatomy. Young stems typically tetragonal, or flattened. Pith very heterogeneous. Secretory cavities absent. Nodes tri-lacunar, or penta-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 mixed wide and narrow, or narrow.
The wood diffuse porous. The vessels very to moderately small; solitary, radially paired, and in radial multiples. The vessel end-walls oblique; simple, or scalariform and simple. The vessels without vestured pits; without spiral thickening. The axial xylem with tracheids, or without tracheids; without vasicentric tracheids; with fibre tracheids, or without fibre tracheids; with libriform fibres, or without libriform fibres; including septate fibres. The fibres without spiral thickening. The parenchyma wanting. The secondary phloem not stratified. Included phloem absent. The wood not storied.
Reproductive type, pollination. Plants hermaphrodite, or dioecious, or gynodioecious. Female flowers with staminodes, or without staminodes (androecium vestigial). Gynoecium of male flowers vestigial.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in inflorescences; in cymes and in panicles. The ultimate inflorescence units cymose. Inflorescences terminal, or axillary; branching cymes. Flowers small; regular; cyclic. Free hypanthium absent. Hypogynous disk present (adnate to the calyx); intrastaminal; annular (hairy, notched).
Perianth sepaline; (4–)5(–8); 1 whorled. Calyx (4–)5(–8); 1 whorled; gamosepalous (shortly connate below); 48 blunt-lobed. Calyx lobes markedly longer than the tube. Calyx regular; persistent; valvate.
Androecium 8–10(–14). Androecial members branched (in that the members of the inner, antesepalous set are sometimes paired, and up to twice as many as in the outer set), or unbranched; free of the perianth; free of one another; 2 whorled. Androecium exclusively of fertile stamens. Stamens 8–10(–14); diplostemonous to triplostemonous; alternisepalous; filantherous (the filaments hairy). Anthers dorsifixed; versatile; dehiscing via longitudinal slits; introrse. Pollen grains aperturate; 3 aperturate; colporate.
Gynoecium (2–)4–5(–8) carpelled; apocarpous; eu-apocarpous; superior. Carpel stylate; apically stigmatic (the style slender, elongate, recurved or almost circinnate, the stigma decurrent along its sulcus); 2 ovuled. Placentation marginal (the ovules near the middle of the ventral suture). Ovules pendulous; epitropous; collateral; non-arillate; anatropous; bitegmic; presumed crassinucellate.
Fruit non-fleshy; an aggregate. The fruiting carpel dehiscent; a follicle (with a dense, short reddish to yellowish indumentum, plus longer, straight, lignified, pointed hairs. Each follicle becoming abaxially distorted to bring the style outwards or downwards). Seeds copiously endospermic. Embryo well differentiated (large). Cotyledons 2 (flattened). Embryo straight. Micropyle not zigzag.
Seedling. Germination phanerocotylar.
Geography, cytology. Neotropical. Tropical. America.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgrens Superorder Rosiflorae; Cunoniales. Cronquists Subclass Rosidae; Rosales. APG III core angiosperms; core eudicot; Superorder Rosanae; fabid. APG IV Order Oxalidales.
Species about 60. Genera 1; only genus, Brunellia.
Illustrations. • Brunellia comocladifolia (Hutchinson).
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. delta-intkey.com/angio’.