The genera of Leguminosae-Caesalpinioideae & Swartzieae
Type species: B. sollyaeformis Baill.
Habit and leaf form. Trees and shrubs (with dense wood, the trunk sometimes deeply folded and fluted); unarmed.
Phyllotaxy spiral. The leaves ostensibly simple (unifoliolate and entire, apically obtuse and pinnately veined); with a predominant midrib. Stipules present, persistent and conspicuous in mature leaves, or absent or early caducous or very inconspicuous in mature leaves; leafy, or membranous. Stipels absent.
Inflorescence and floral morphology. The inflorescences small, axillary, or axillary and terminal; unbranched, or branched (often, basally); of racemose units. The flowers not distichous. Bracts small, absent at anthesis (caducous). Bracteoles absent at anthesis.
The flowers small to large (to 1.5 cm in diameter); hermaphrodite; actinomorphic to slightly irregular (subactinomorphic); pentamerous, or not pentamerous throughout; departing from pentamery sometimes in the androecium; coloured. Hypanthium absent, the androecium hypogynous. The perianth comprising distinct calyx and corolla. Calyx present; 5; covering the rest of the flower in bud; polysepalous; more or less regular; members imbricate. Corolla present; regular to slightly irregular; 5; without greatly reduced members. Well developed petals 5. Corolla polypetalous. Petals oblong-elliptic, sessile; imbricate; supposedly imbricate-ascending (?); yellow. Disk absent. The androecium comprising 10 members, or 7–10 members; not declinate; members all free of one another; members all more or less equal in length (subequal, with short filaments); comprising only fertile stamens. Fertile stamens 7–10. Anthers linear-oblong, attached at the base of the connective; dehiscing via pores or short slits. Ovary shortly stipitate; free. Stigma not dilated (the style acicular). Ovules in the different species, few to numerous (2–25).
Fruit, seed and seedling. Fruit indehiscent; drupaceous (then with a thin pericarp and a woody interior, with (1-)2–4 seeds in individual chambers), or not drupaceous (then a leguminous to fleshy lomentum that separates into 25(-3) separate segments); internally septate; without markedly twisting or enrolling valves; becoming woody (with hard endocarp), or not becoming woody. Seeds not arillate; with a straight or slightly oblique radicle.
Transverse section of lamina. Leaves with conspicuous phloem transfer cells in the minor veins. Druses absent from the mesophyll. Mesophyll secretory cavities absent. Adaxial hypodermis absent. Leaf girders common (the veins transcurrent). Laminae dorsiventral. Mesophyll without unaligned fibres or sclereids. Minor veins mainly with abundant accompanying fibres.
Leaf lamina epidermes. Epidermal crystals not seen either adaxially or abaxially. Simple unbranched hairs common; scabrid. No compound or branched eglandular hairs seen. Capitate glands not seen. Hooked hairs not seen. Cassieae-type leaf pseudo-glands not seen. Expanded and embedded hair-feet absent. Adaxial: Adaxial interveinal epidermal cell walls straight in optical section; conspicuously pitted; thick. Stomata adaxially very rare. Abaxial: Abaxial stomata not predominantly paracytic (actinocytic and anomcytic). Abaxial epidermis not papillate. Abaxial interveinal epidermal cell walls straight, or gently undulating; conspicuously pitted in optical section; staining normally with safranin; medium-thick.
Pollen ultrastructure. Tectum punctate; rugulose punctate. Length of colpi greater than one half pole to pole distance.
Species number and distribution. About 6 species (e.g., B. fluggeiformis, B. sollyaeformis, B. rouxevillei). Madagascar.
Comments. Including some sources of wood.
Miscellaneous. Illustrations: • B. sollyaeformis: Baillon, Adansonia VI (1865). • B. fluggeiformis leaflet: abaxial epidermis (general view). • B. fluggeiformis leaflet: detail of abaxial epidermis.
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, and classification. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1993 onwards. The genera of Leguminosae-Caesalpinioideae and Swartzieae: descriptions, illustrations, identification, and information retrieval. In English and French. Version: 22nd March 2017. delta-intkey.com/caes’.