Unarmed large bushes or small to medium-sized trees; outer bark often peeling in papery flakes, under-bark greenish with a watery aromatic exudate hardening to a resin; wood soft, often with a milky latex. Leaves usually clustered at the ends of branches, usually imparipinnate but 1-foliolate or hetero–3-foliolate in 2 Socotran species; stipules sometimes present, caducous; leaflets often subalternate, variously crenate or serrate, or entire. Inflorescence a panicle or raceme. Flowers bisexual or (in B. madagascariensis) dioecious. Calyx 5-lobed, persistent. Petals 5, free. Stamens inserted outside a conspicuous annular disc, 10 in 2 whorls of 5, the outer usually having broader filaments than the inner. Ovary (2–)3(–4–5)-locular or, in B. frereana Birdwood from N. Somalia, (5–)6(–8)-locular; style simple; stigma capitate. Fruit an obovoid pseudocapsule with (2–)3(–4–5) angles, the outer walls breaking away to disclose a (2–)3(–4–5)-winged axis with a 1-seeded nutlet in each compartment between the wings; nutlets at first surrounded by a fragile outer layer which may form a temporary wing. Cotyledons 3-or 5-lobed or 3-lobed with both lateral lobes bifid. Fig. 3/1,2, p. 10.
Home