Funastrum is a genus of twining flowering plants in the family Apocynaceae (the dogbane family), order Gentianales. The genus comprises around 21 accepted species and is distributed across the Americas, from the southwestern United States south through Mexico, Central America, and into South America.
Members of the genus are herbaceous to somewhat woody vines that climb by twining their stems around supporting vegetation. This growth habit gives the genus its name and its collective common name, twinevines. The flowers are small and five-petaled, typical of the milkweed subfamily (Asclepiadoideae), and are adapted for insect pollination. Several species bear distinctive fringed or hairy petals, as in Funastrum cynanchoides (fringed twinevine) and Funastrum hirtellum (hairy milkweed).
The genus was formerly placed within Sarcostemma, and species were long treated under that name before molecular studies and taxonomic revision led to their transfer to Funastrum. Well-known members include Funastrum clausum (white twinevine), Funastrum crispum (wavyleaf twinevine), and Funastrum utahense, which occurs across arid portions of the Great Basin and Colorado Plateau.
Etymology
The genus name Funastrum derives from the Latin funis, meaning "rope," combined with astrum, a suffix often used in botanical Latin to denote resemblance. Together they allude to the rope-like twining stems characteristic of the genus, which is also reflected in the common name twinevines.
Distribution
Funastrum species are distributed across the Americas. Several species are native to the arid and semi-arid regions of the southwestern United States (including Utah, Texas, and California), with others extending through Mexico and Central America into South America, including the Andes and Brazil.
Taxonomy Notes
Funastrum was for a long time subsumed within the broader genus Sarcostemma. Phylogenetic studies in the Asclepiadoideae subfamily of Apocynaceae supported its recognition as a distinct genus. The genus is placed in the order Gentianales within the class Magnoliopsida. As of 2023, Plants of the World Online accepts 21 species in the genus.
