Tansy-mustards are annual or biennial herbs, usually branched, with short, star-shaped hairs or sometimes almost hairless. The hairs sometimes have stalked glands. The leaves are pinnately compound once to 3 times, the ultimate segments usually rather narrow. The flowers are inconspicuous, borne in dense clusters without bracts. The 4 sepals are spreading. The 4 petals are yellow to cream, with a lower, narrowed part called the claw. There are 6 stamens. The fruit pods are small, linear to narrowly club-shaped, usually nearly cylindrical, or somewhat 4-sided due to the prominent nerves of the valves. The inner partition is nerveless to lightly 3- nerved. The style is inconspicuous and the stigma small, entire. The seeds are arranged in 1 row or partially in 2 rows, becoming slimy when wet. The genus has about 30 species, chiefly of temperate N. and S. America, a few of them Eurasian. The name comes from Francois Descurain, a French apothecary and botanist.
Guide to Identify Presented Species of Genus Descurainia
LEAVES WITH NARROW, POINTED SEGMENTS
D. pinnata – Western Tansymustard Annual, 10-70 cm tall, green or grayish-short-hairy. Flowers yellow, ca 5 mm wide, petals slightly longer than sepals. Leaves once pinnate with linear segments. Plains, hills.
D. sophia – Common Tansymustard Annual, 30-100 cm tall, often gray-short-hairy. Flowers yellow, ca 2 mm long, petals slightly shorter than sepals. Leaves at least twice pinnate with narrow segments. Plains, hills.
