Asclepiadaceae

Asclepiadaceae, commonly known as the milkweed family, was historically recognized as a distinct family of flowering plants in the order Gentianales. In modern classifications it is treated as the subfamily Asclepiadoideae within the family Apocynaceae, though some sources still list Asclepiadaceae as a separate family. The group includes herbaceous perennials, shrubs, and climbers distributed across tropical and subtropical regions worldwide, with particularly high diversity in Africa, Asia, and the Americas.

A hallmark of many Asclepiadoideae species is the presence of milky latex containing cardiac glycosides (cardenolides), which can deter herbivores. Leaves are typically opposite or whorled. Flowers are often showy and arranged in umbels or similar inflorescences; they usually have five petals and a complex corona that forms part of a specialized pollination mechanism. Pollinia—paired masses of pollen—attach to visiting insects, guiding pollination as the insects contact the flower’s reproductive structures and transfer the pollinia to the next flower. Nectar is produced within the corona or adjacent structures.

Genera include Asclepias (milkweeds), Calotropis, Cynanchum, Gomphocarpus, and the succulent Stapelia, Orbea, and Huernia, among others. Many species are cultivated ornamentally for their attractive flowers, and some have traditional medicinal uses or are valued for latex or fiber. Ecologically, several species serve as host plants for certain butterflies and other insects, while their toxins influence herbivore interactions.

Taxonomic changes have prompted ongoing review of the group’s circumscription and relationships within Apocynaceae, reflecting advances in molecular phylogenetics.