Cocklebur is a rough-to-the-touch annual forb that grows up to five feet tall, generally two to four feet tall. The stout stems are purplish-green with purple or black spots. Alternate leaves are large and broad and up to six inches long. They are triangular or heart-shaped (deltoid or cordate) with wavy and toothed margins, and they arise on long petioles. The plant is monecious, meaning the flowers are borne on one plant; however, there are separate male and female flowers. The greenish female flowers are clustered in leaf axils throughout the plant, while the male flowers occur in clusters towards the top of the plant. Flowers are tiny in size. The female flowers, which lack a corolla, give rise to the oval-shaped, two-chambered bur. These fruits are about one inch long, brown, and they are covered with long, stiff, hooked spines. The fruits form in the late summer and turn from green to brown with age.