A native of Europe, now common throughout the western states.
A winter annual that may also be found in the summer in cool, shaded locations. It prefers damp soils and is a problem in irrigated crops, along roadsides, and in irrigation ditches.
Reproduction is from seeds that germinate in the late fall and winter.
Mature plants can grow as high as 4 feet, but vary widely depending on the conditions they are growing in. Stems often are branched and may form a dense plant. Stems and leaves generally are without hairs.
Leaves are as long as 8 inches and are deeply lobed, forming a number of leaflets on the leaf stalk. The terminal lobe is somewhat pointed.
Flowers are typical yellow, in small clusters at the ends of the stems. Seed pods develop below the flower cluster, and may grow to 2.5 inches long.
Characteristicts Important to Control:
Germination is early, with cool, wet winter conditions.