Flowers are similar to those of Indian Milkweed (Asclepias eriocarpa, see above). However, these appendages are more cup-shaped than hooded, and the horn is strongly exserted. Petals are green-white with a purplish tinge. Leaves are narrow, glabrous and opposite or whorled in 3s or 5s. There are often smaller leaves in the axils. Fruits are erect, long and narrow.