Most members of the family are poisonous, as the common name for the entire family, Dogbane , indicates. The chemical alkaloid contained in the roots and stems of various family members, such as Rauwolfia species , have in recent years, come into prominence chiefly because of their effectiveness in reducing blood pressure as well as their us as tranquilizers. The Madagascar periwinkle has proven effective in treating a particular childhood leukemia. Species of Strophanthus are known mostly as deadly arrow poisons. Another interesting member of this great family of plants, is called Aspidosperma quebracho-blanco , an enormous tree from Argentina, Chile and Bolivia.
All family members exude a milky latex.
The flowers are hermaphrodite and regular, that is, the male and female flowers are borne on the same plant. Tabernanthe iboga is a shrub to small tree attaining up to two meters in height. It is widely cultivated in Gabon by the Bwiti and Mbiri people for its root bark. This bark is ingested in a ceremonial ritual whereby the participants travel on the astral plane to meet with their ancestors. There is singing, dancing and drumming until a high state of excitement is reached under the influence of the plant.