COMMON COCKLEBUR, Xanthium strumarium L. 1, upper part of plant; 2, seed; 3, bur; 4, seedling plant. Annual, reproducing by seed. Taproot rather woody, stout. Stem erect, non-nally bushy, 2 to 4 feet (0.6 to 1.2 m) tall, ridged, rough-hairy, often spotted. Leaves alternate, simple, triangular in outline, toothed or lobed, rough, with long petioles. Flowers small, male and female flowers separate but borne together in clusters in axils of the upper leaves. Two female flowers are enclosed in each oval bur. At maturity the bur is hard, woody, and covered with hooked prickles, and ends in 2 curved spines. Male flowers numerous, in clusters on short stalks, dropping soon after pollen is shed. Seeds about 1/2 inch (1.3 cm) long, dark brown, rather slender with pointed tips. Found in cultivated fields, abandoned land, poor pastures, and roadsides.