Family: Asteraceae, Aster view all from this family
Description Introduced. A slender, branched, grayish-hairy plant with wing-like ridges along stem and small, rayless, bright yellow flower heads with lustrous, sharp, golden spines.
Flowers: Head about 1/2-5/8" (12-16 mm) wide, slightly longer; spines each 3/8-1" (1-2.5 cm) long, spreading.
Leaves: Those at base 2-3" (5-8 cm) long, deeply lobed; those on stem smaller, not lobed, bases continuing down stem with wing-like ridges.
Height: 4-39" (10-100 cm).
Warning This plant grows in dense stands that are painful to walk through because of the piercing spines. If continually eaten, it is poisonous to horses. Both horses and cattle have been known to develop infections of the lips and tongue from eating hay contaminated with the spines.
Flower May-October.
Habitat Disturbed areas, pastures, and dry grasslands and hillsides.
Range Washington south to California and east to Utah and Idaho.
Discussion Native to Europe, this invasive plant is spreading across the western United States. Its one virtue is that it produces a fine light honey. This unloved weed is a relative of Bachelor's Button (C. cyaneus). A similar but less showy plant, Tocolote (C. melitensis), has smaller spines on the flower heads, the longest only about 1/4-3/8" (5-10 mm) long; it, too, has been introduced from Europe and is rapidly spreading in western North America.
