Origin:
Native to Eurasia, and now found throughout the United States.
Biology:
Normally a winter annual, although it will grow as a summer annual in the proper wet conditions. Reproduction is by seeds that germinate in late summer, early fall, or in the spring. Seeds may remain viable in the soil for many years, with over a thousand seeds possible from a single plant.
Identification:
Mature plants have two forms - those with hairy, prickly stems and those with smooth stems. The plants grow to as tall as 3 feet, with multiple, branching erect stems. Leaves can be 8 inches long and thickly clustered around the base. Leaves on the lower stems are deeply lobed at the base and have long petioles, while upper leaves are simple and generally without stems or petioles. Flowers are yellow and with 4 petals. The seed pods (siliques) that develop along the stem can be 2 inches long, beginning very slim and enlarging to about 1/4 inch in diameter. These are on short pedicels, and there is a constricted beak at their end that is about half the length of the silique.
Characteristicts Important to Control:
A winter annual germinating in early fall through the winter and into spring. It may be found in any growing condition, and propagates only from seed.
