Native to the Mediterranean area, but now found in several states from Oregon to Texas, and sporadically along the east coast.
Potentially a serious weed pest, and currently listed as a noxious weed in Australia. A closely related species is a Class A listed noxious weed in Oregon. This is a winter annual, forming a rosette through the winter, and with the warm weather developing the erect, rigid stems. Reproduction is from seeds. Dead plants will persist for long periods as dry plant parts. Found along roadsides and in disturbed sites, pastures, and often in grain fields, where they cause problems with contamination of the crop when harvested.
Plants begin as a low rosette of foliage in the winter, with thick, rigid stems arising in the spring. Leaves are alternate along the stems, clasping the stem without stalks, and tend to bend downward at their tips. The leaves are narrow and long, with short, narrow lobes along their margins, each lobe equipped with a spine. The stems are profusely covered with long whitish hairs. Flower heads grow at the ends of the stems, with a large, very spiny receptacle below the yellow flowers, which are also surrounded at their base by another circle of long spines.
Characteristicts Important to Control:
Mowing or physical removal just prior to flower head formation is necessary to prevent seed development.