Many species are native to or naturalized in North America.
Members of the family are sources of such economically important products as drugs and tannins. The vincristine alkaloids that are so effective in the treatment of Hodgkin's disease were discovered in the Madagascar periwinkle, Catharanthus roseus. Dogbane is classified in the division Magnoliophyta , class Magnoliopsida, order Gentianales. Listing from Electric Library , a pay service. No relevant pictures or maps found.