Apocynaceae

Lore & Background

The family Apocynaceae is morphologically diverse, including annual plants, perennial herbs, stem succulents, woody shrubs, trees, and vines. Most exude a milky latex when cut.

Leaves are simple, usually opposite and decussate, without stipules or with small finger-like stipules. Flowers are complex, radially symmetric, bisexual, with a five-lobed calyx and five petals united into a tube. The fruit can be a drupe, berry, capsule, or follicle, and seeds are often winged or have long silky hairs.

Species are distributed mainly in tropical regions, from tall evergreen trees in Indomalayan forests to smaller trees in African and Indian deciduous forests, and lianas in South America, Africa, and Madagascar. In temperate Europe, only Vinca and Vincetoxicum are found. In North America, Apocynum (dogbane) was a traditional source of fiber. Several genera are preferred larval host plants for the Queen Butterfly.

Many species are toxic, with some extremely poisonous if ingested. Genera containing cardiac glycosides—such as Cerbera, Nerium, and Asclepias—have therapeutic ranges but are associated with accidental poisonings. Alkaloid-producing species like Rauvolfia serpentina and Catharanthus roseus are sources of compounds with therapeutic ranges but significant toxicities if not used appropriately.

Reader's Guide

Apocynaceae holds significance as a family of plants with profound economic, medicinal, and toxicological importance. Several members have been sources of important natural products, including cardiac glycosides affecting heart function, and alkaloids used in treating hypertension, cancer, and drug addiction. For example, Rauvolfia serpentina contains reserpine, used as an antihypertensive and antipsychotic, while Catharanthus roseus yields cancer-treating alkaloids. The family also includes plants used traditionally as hallucinogens (Tabernanthe iboga) and arrow poisons (Acokanthera species).

Many genera are grown as ornamentals, such as oleander, periwinkle, and frangipani. Some have been used for rubber production (Landolphia) or fiber (Apocynum). Limited dietary uses exist, such as the edible fruit of Carissa and the flower of Echites panduratus. The family's toxicity requires careful handling, but its contributions to pharmacology and horticulture are substantial.

Did You Know?

• Many species exude a milky latex when cut, including Adenium species, which also produce milky latex, not clear sap.
• The former family Asclepiadaceae is now considered a subfamily (Asclepiadoideae) of Apocynaceae.