WILD MUSTARD, Brassica kaber (DC.) Wheeler. 1, lower part of plant; 2, upper part of plant; 3, leaf from upper part of stem; 4, flower cluster; 5, seed pods; 6, seed. Annual or winter annual, reproducing by seeds. Stems erect, branched near top, with a few bristly hairs. Leaves: lower ones irregularly lobed, toothed, with petioles and with bristly hairs; upper leaves smaller, often not lobed, alternate, with no petioles or short ones. Flowers conspicuous, with 4 yellow petals, in clusters at the ends of branches. Seed pod slender, on a spreading stalk; 1 inch (2.5 cm) or more long, about 1/3 of length being an angular beak at the tip. Seeds round, black, bluish, or brown, smooth and hard, about 1/16 inch (1.5 mm) in diameter. Found commonly in grain fields and occasionally in other cultivated crops. A troublesome weed in many areas. Seeds live in the soil for many years. Also commonly known as charlock.