Green antelopehorn, or spider milkweed, grows in pine woods, dry fields, and roadsides in southern parts of the United States. Each 18-inch stalk is topped by a large umbel of flowers. The jade green outer petals, or corolla lobes, are slightly cupped forward. Five spoon-shaped pink to purple petals with white spots nestle in the center. In late summer to fall, narrow, 4-inch long, curved follicles (seedpods) form and split open, releasing seeds with silky tufts. Like most milkweeds, the alternate leaves exude an irritating milky sap. It is found in the southernmost counties of Illinois but is more abundant in Kansas and Texas, where it is an important species to migrating monarch butterflies. Plants do not transplant well due to long rhizomes, and seed requires a cold treatment before sowing in spring. Once established, this species is tolerant of all kinds of soils and is draught-tolerant.