34. Ricinus Linnaeus, Sp. Pl. 2: 1007. 1753.
蓖麻属 bi ma shu
Authors: Huaxing Qiu & Michael G. Gilbert
Annual herbs or herbaceous shrubs; indumentum absent; stems hollow. Leaves alternate; stipules united, deciduous, leaving circular scar around node; petiole long, apex with 2 glands, insertion peltate; leaf blade palmately lobed. Inflorescences terminal, branched or unbranched, bisexual; bracts broadly triangular, deciduous; male flowers proximal, female flowers distal. Male flowers: calyx 3-5-lobed, valvate, closed in bud; petals absent; disk absent; stamens very many; filaments united into ca. 25 phalanges; anthers 2-locular, subglobose. Female flowers: sepals 5, valvate, deciduous; petals absent; ovary 3-locular, softly spiny, sometimes tuberculate; styles 3, 2-lobed. Fruit a capsule, 3-locular, usually echinate. Seeds large, compressed-ovoid, smooth, marbled, carunculate.
One species: widely cultivated in tropical to temperate regions and frequently occurring as a ruderal weed; fossil remains suggest that it is perhaps native to NE Africa.