Apocynaceae

Family of dicotyledonous shrubs or plants, having about 130 genera and 1,100 species, mostly tropical, many with poisonous milky juice. The flowers have five petals which are joined at the base to form a tube, but generally spread out flat above.

The family includes Apocynum cannabinum (Indian hemp, also classified as Cannabis sativa) and several rubber-yielding genera, for example Landlophia and Urceola. In Great Britain the greater and lesser periwinkle (Vinca major and V. minor) occur.

The ordeal tree, Cerbera, of Madagascar is very poisonous. The Natal plum Carissa grandiflora and other species produce edible fruits. Catharanthus (Vinca) rosea, a common tropical weed, has been found to give a drug, cytoblastin, which acts against certain cancers.