A common shrub or understorey tree to about 17 m high of the closed-forest and in secondary regrowth, occurring from Guinea to W Cameroons and Fernando Po, and extending to Zaïre.The leaves and fruit are bitter, and are very poisonous causing drastic purging. The Mende name ŋwaŋwui or nwangwai, meaning ‘bitter-bitter’, has been adapted in Sierra Leone Krio to nσmba-wan, i.e., ‘number one’, and this term has been carried to other parts of West Africa, in respectful acknowledgement of the plant’s dangerous toxicity (7, 13). Even in Fernando Po it carries this name where it has been recorded that the plant is a powerful drastic purgative dreaded greatly by the natives for its poisonous qualities, having killed many people (8). In Ghana Akan peoples know it as ‘medicine executioner’ from odu(ru): medicine and (σ)brafo: executioner (9). The Basa of Liberia use it as an ordeal-poison (2).A decoction of leaves, or the leaf-sap, is known everywhere as a violent purgative and abortifacient. A dozen leaves boiled in a pint (c. half a litre) of water is said to be a safe dose in Ghana, but any stronger is dangerous, and in Ghana and Liberia it is never given to pregnant women, nor to children, nor old persons (7, 9). After an abortion a single leaf in food ensures removal of the afterbirth, and a small dose is repeated for some days (7). In Ivory Coast-Upper Volta medicine-men consider it a valuable drug-plant prescribing it for diseases the treatment of which requires violent action on the intestines, e.g., ascaris infection, blennorrhoea and especially leprosy (3. 10). The bark with other drug-plants is used topically for leprosy in Liberia (7). In Sierra Leone water in which dried leaves have been boiled is given to children as a worm-treatment (13).An over-dose or criminal poisoning will cause complete exhaustion by purging (5, 16), and leaves produce hypotension in dogs (12), and root-extracts coma and paralysis of the respiratory centres in rats (15). Antidotal treatment has been reported to be red palm-oil (5) or raw cassava (7).The plant has analgesic and anaesthetic properties. It is widely used internally as an anodyne for headache and stomach-pains, and externally topically on fractures, stiffness, sprains, lumbago and rheumatism; also on sores and ulcers. The powdered root is used in Ivory Coast-Upper Volta on snake-bite and the stings of venomous animals (10). Leaves are crushed up to a paste with a little soil and water in Ivory Coast for rubbing into areas of rheumatic pains and for kidney pains (1), and a paste of leaves, pepper and citron is applied, with frequent renewal, to a guinea-worm sores (10). The pounded bark, sometimes mixed to a paste with a sort of white clay, is applied topically and a leaf-decoction taken internally for craw-craw (7). In Sierra Leone burnt leaves are ground up with clay for application to the body for scabies (13). Also in Sierra Leone the leaf in decoction is taken for malaria, and the bark along with that of Zanthoxylum gilletii (syn. Fagara macrophylla, Rutaceae) and the leaf of Microdesmis puberula (Pandaceae) and new black soil from on top of a termite heap is ground to a paste for paralysis of the limbs in topical massage (11). Fermented leaves, with rum and coconut, are taken by draught in Ghana for cough and weakness and in small doses for blackwater fever (7, 9).Though the plant is very plainly pharmacologically active, there remains some doubt regarding the identity of the active principles. Sierra Leone material has shown alkaloids absent but saponins present (14). Ivory Coast material has not shown the presence of any simple active principle, neither alkaloid, saponin, nor bitters, but other work suggests the presence of toxic triterpenic substances of the cucurbitacin group (3, 10).The wood is white, soft and perishable. It sinks when fresh, but later floats (4). The sterns are commonly used for yam stakes.Birds avoid eating the fruit.