var. hartwegii (Vail)
Climbing milkweed is a perennial desert shrub with green, twining or straggling, 3'-6' glabrous to puberulent stems and having opposite, linear to lanceolate leaves that either are clasping or short-petiolate. The flowers are several in umbels on peduncles up to 2" long. The five calyx lobes are short and the corolla is purplish with white margins that are densely pubescent, and also five-lobed. There are five stamens with the filaments in a column and the anthers having an orbicular appendage that rises from a ring of tissue at the base of the corolla. There is generally a single fruit which is a slender, fusiform follicle 2"-4" long. Climbing milkweed usually grows among shrubs and small trees in dry rocky washy and flats below 2000' (-4500') in both deserts, and also sometimes in coastal sage scrub and chaparral. It ranges to Utah, Arizona and Mexico, blooming from April to July. It can be easily distinguished from its close relative, F. hirtellum, which has a greenish-yellow corolla. These pictures were taken in Torrey Pines State Park.
Click here for Latin name derivations: 1) Funastrum