Monographs Details: Forsteronia corymbosa (Jacq.) G.Mey.
Authority: Britton, Nathaniel L. Flora Borinqueña.
Description:Species Description - Known also by the Spanish names Sanjuanera and Leche de perra, this attractive, high-climbing vine, with dark green leaves and clustered, small red or purple flowers, inhabits forests and thickets, and is frequent in such situations in wet and moist parts of Porto Rico, ascending to higher elevations, it is distributed through Santo Domingo and Cuba, and recorded as also found in Guiana. The curious cylindric fruits, composed of two follicles which spread widely nearly in line with each other, are very interesting. Only one species of the genus inhabits Porto Rico. Forsteronia, dedicated by the botanist G. F. W. Meyer in 1818 to Furley Forster, without recording who he was, is a genus of some 30, or more, species of tropical American, woody vines, the one here illustrated typical; they have opposite, untoothed leaves, and small, regular flowers in terminal clusters. The calyx is 5-parted, the corolla salverform, with a short tube and a 5-lobed limb; the 5 stamens, borne on the corolla-tube, have short filaments and appendaged anthers. The ovary is composed of 2, separate carpels, the short style topped by an ovoid stigma. The fruit consists of 2, slender, nearly round follicles, containing many, narrow seeds with a tuft of hairs at the end. Forsteronia corymbosa (referring to the broad flower-clusters) is a smooth vine which may become 7 meters long, or longer. The oval, or elliptic, shining, thick leaves are from 4 to 8 centimeters long, pointed, or blunt, with stalks about 8 millimeters long, or shorter. The flowers form clusters from 4 to 8 centimeters broad, the individual ones on short stalks; the oblong, blunt calyx-lobes are about 2 millimeters long, the red, or purple corolla about 6 millimeters long, with lobes longer than the tube. The straight, widely divergent pods are about 8 centimeters long.

Discussion:Bejuco de San Juan Vine of Saint John Dogbane Family Echites corymbosa Jacquin, Enumeratio Systematica Plantarum 13. 1760. Forsteronia corymbosa Meyer, Primitiae Florae Essequeboensis 134.1818.