The smooth, stout, unbranched stems of this milkweed generally occur in spreading clusters which ascend 1-1 1/2 ft. The spreading habit; 5-10 pairs of broad, clasping leaves; tan-colored flowers buds; a nearly white crown; and erect fruits on drooping pedicels are the perennial’s prominent features. Leaves are distinctly purple-veined and the white flowers sometimes have a touch of lavender.
Humistrata means low growing or sprawling, a term that fits the prostrate growth form of this species with stems that are flat or nearly flat to the ground. Stems are purplish, a color that continues along the veins into the dull green leaves.