apocynaceae

Apocynaceae, commonly known as the dogbane family or, in broad circumscription, the milkweed family, is a large family of flowering plants consisting of about 5,000 species in roughly 400 genera. The group is cosmopolitan, most diverse in tropical and subtropical regions, but with representatives in temperate zones. Members range from herbaceous perennials to shrubs, lianas, and small trees, and many produce milky latex.

Morphology and flowers: Leaves are usually opposite or whorled and simple. The flowers are typically showy, actinomorphic or slightly zygomorphic, and often arranged in cymes or umbels. Many genera have five-parted flowers with five petals and five sepals; in the subfamily Asclepiadoideae (milkweeds) the flowers are highly specialized and often bear a corona and pollinia, adapted for insect pollination. Fruit is usually a pod-like follicle or a berry, often with paired follicles; seeds may have tufts of silky hairs in milkweeds. Latex is common in many species.

Taxonomy and classification: Apocynaceae is placed in the order Gentianales. In modern classifications (APG system), Asclepiadoideae is treated as a subfamily within Apocynaceae rather than a separate family (historically Asclepiadaceae). The family is subdivided into several subfamilies, including Apocynoideae, Rauvolfioideae, and Asclepiadoideae, with many genera of ornamentals and ecologically important species.

Uses and notable species: Many Apocynaceae are cultivated as ornamentals, including Nerium oleander, Plumeria, Vinca, Catharanthus roseus, and Hoya. The family contains toxic compounds such as cardiac glycosides; some species are highly toxic if ingested. The Madagascar periwinkle (Catharanthus roseus) provides alkaloids vincristine and vinblastine used in cancer chemotherapy. Other members have traditional medicinal uses or serve as nectar sources for pollinators.