Centaurea soltitialis

Background: Yellow starthistle is native to the Mediterranean region; and also found in western and central Asia.

Identification: This plant is an annual weed that grows 2-3 feet tall. It has rigid branching, winged stems that are covered with a cottony layer (pubescence). Basal leaves are deeply lobed while upper leaves are entire and sharply pointed. Flower heads are yellow, located singly on the edges of the branches. The flowers have sharp straw-colored thorns that are ¾ inch long. Seedling plants typically appear in winter and early spring, but can germinate any time between November and July.

Distribution: Yellow starthistle grows in various soil types and usually appears first on roadsides and waste areas. It also grows in fallow fields, pastures, and rangelands; mostly at low elevations. The plant is a noxious weed in fields of alfalfa and small cereals (wheat, oats, barley, and rice).

Control: Contact local pest control advisor.

Photo by:  Jack Clark, University of California, Integrated Pest Management