The genera of Leguminosae-Caesalpinioideae & Swartzieae
Type species: B. parviflora Benth. ex Bak.
Habit and leaf form. Trees, or shrubs; unarmed.
Phyllotaxy spiral. The leaves ostensibly simple (symmetrical, pinnately veined from the midrib); with a predominant midrib. Stipules absent or early caducous or very inconspicuous in mature leaves; membranous. Stipels absent.
Inflorescence and floral morphology. The inflorescences axillary (or from older branches); unbranched; simple racemes, or simple corymbs (or umbels). The flowers not distichous. Bracteoles present; small, not enclosing the flower buds; persistent beyond anthesis.
The flowers small; hermaphrodite; not papilionaceous; not pentamerous throughout; departing from pentamery in the calyx, in the corolla, and in the androecium. Hypanthium absent, the androecium hypogynous. Calyx 1–5; Swartzieae type (closed before flowering, splitting more or less irregularly into valvate lobes or teeth); gamosepalous; more or less regular, or markedly irregular; members not imbricate. Corolla present; slightly irregular; 6; without greatly reduced members; polypetalous. Petals imbricate; imbricate-ascending. Disk absent. The androecium comprising 14–18 members; members all free of one another; members markedly unequal; comprising only fertile stamens. Fertile stamens 14–18. Anthers attached well above the base of the connective; dehiscing longitudinally. Ovary sessile or subsessile; free. Stigma not dilated. Ovules few.
Fruit, seed and seedling. Fruit without markedly twisting or enrolling valves; not becoming woody. Seeds non-endospermic; arillate; with an inflexed radicle; amyloid-negative.
Transverse section of lamina. Leaves without 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. No compound or branched eglandular hairs seen. Capitate glands not seen. Expanded and embedded hair-feet absent. Adaxial: Adaxial interveinal epidermal cell walls markedly sinuous in high-focus optical section; not conspicuously pitted; thick to medium-thick. Stomata adaxially very rare. Abaxial: Abaxial stomata predominantly paracytic. Abaxial epidermis not papillate. Abaxial interveinal epidermal cell walls markedly sinuous in high-focus optical section; not conspicuously pitted in optical section; staining normally with safranin; medium-thick.
Species number and distribution. 1 species (B. parviflora). Tropical Africa.
Miscellaneous. Illustrations: • B. parviflora: Brenan, Fl. Tropical East Africa (1967). • B. parvifolia: Aubréville, Flore du Gabon (1968).
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’.