Castor bean, castor oil plant [Latin, tick or louse, alluding to appearance of seeds] Castor bean, castor oil plant [Latin, tick or louse, alluding to appearance of seeds]

Lynn J. Gillespie

Herbs [shrubs], annual or perennial, monoecious; hairs absent; latex absent. Leaves deciduous, alternate, simple; stipules present, caducous; petiole present, glands present at apex and usually proximally; blade palmately lobed, margins serrate, laminar glands present; venation palmate. Inflorescences bisexual (staminate flowers proximal, pistillate distal) or pistillate, terminal or leaf-opposed, racemelike thyrses; glands subtending each bract 2. Pedicels present. Staminate flowers: sepals 3–5, valvate, connate basally; petals 0; nectary absent; stamens to 1000, connate proximally in numerous slender, irregularly branched columns; pistillode absent. Pistillate flowers: sepals 5, distinct or connate basally; petals 0; nectary absent; pistil 3-carpellate; styles 3, distinct or slightly connate basally, 2-fid. Fruits capsules. Seeds ovoid or ovoid-ellipsoid; caruncle present. x = 10.

Species 1: introduced; ne Africa; widely cultivated and often naturalized in tropical, subtropical, and warm temperate regions worldwide.

Lower Taxon

• Ricinus communis Linnaeus