Asclepias asperula is a clump-forming, 1-2 ft. perennial with an upright or sprawling habit. Stems are densely covered with minute hairs. The leaves are 4-8 inches long, narrow, and irregularly grouped. The long, thick, narrow leaves are often folded lengthwise. As the green seed follicles grow in length and begin to curve, they are said to resemble antelope horns, thus one of its vernacular names.Milkweed species are the food source for Monarch butterfly caterpillars.