Corn cockle is an erect, branched, silky stemmed annual herb that grows up to 3 feet tall. Its oppositely arranged, linear or lanceolate leaves are 3 to 5 inches long, smooth on the margins, and clothed with silky hairs. The red flowers are borne singly at the ends of the branches. The calyx lobes of the flowers are longer than the calyx tubes. A large seed capsule develops within each flower. This seed capsule contains many warty-covered dark-brown or black seeds that are about the size of a grain of wheat.