Flowers, ½ inch in diameter, are formed of 4 petals arranged like a Maltese cross, yellow to orange in color. They are clustered into a round terminal head, the lower flowers of which open first so that usually tubular seed pods (siliques) have formed near the base by the time the top of the cluster is in bloom. Plants are 8 inches or more high, of several stems from one root crown. Grows in foothills, extending down to plains and up through montane zone. Blooms May-July.

The mustards are legion. Fields of them add a yellow note to many western hillsides. They range from weedy poor relations, like shepherd’s purse, to tall, showy spikes of prince’s plume, Stanleya apinnata. Wallflower—despite its name suggesting a colorless personality—is one of the handsome children of the family. Its flowers, larger than most mustards, range in color from pale yellow, through orange, to rich bronze shades. By no means all of the mustards are yellow. The flowers of many of them are white, some, like the cardamine that grows in abundance along sub-alpine water runs, being a very showy, brilliant white.