Madagascar periwinkle, Catharanthus rosea, Apocynaceae.  Uterine stimulant, reduces blood sugar, warming per spirant.  Isolated alkaloids used to treat cancer, especially children's leukemia and Hodgkin's disease.  In the West Indies, it grows profusely, leaf infusion is used to treat diabetes, indigestion and hypertension.  Infusion of leaves also used to treat constipation.  Use only under the supervision of a skilled medical practitioner.  Potentially toxic.