BLACK MUSTARD, Brassica nigra (L.) Koch. 4, seed pod; 5, lower leaf; 6, upper part of plant. Annual, with taproot. Stems erect, branched, growing commonly between 3 and 6 feet (0.9 and 1.8 m) tall; lower parts somewhat hairy. Leaves also somewhat hairy. Upper leaves narrow with elongated petiolelike base. Lower leaves petioled, divided, with large terminal lobe, leaf margins fine-toothed. Flowers yellow, with 4 petals. Seed pods 1/2 to 3/4 inch (1.3 to 1.9 cm) long, lying along stem. Seeds somewhat oval, dark reddish-brown, their surface pitted. Found commonly in waste areas and fields.