Distribution: Occurring chiefly east of the Cascades crest in Washington; British Columbia to California, east across North America to the Atlantic Coast.

Habitat: Noxious weed of sandy soils and roadsides.

Flowers: May-September

Origin: Introduced from Europe and northern Africa

Growth Duration: Annual

Conservation Status: Not of concern

Stiff-hairy, prostrate annual, forming mats 3-10 dm. broad.

Leaves opposite, pinnate; leaflets 4-8 pairs, obliquely oblong-ovate, 5-15 mm. long; stipules 1-2 mm. long.

Flowers solitary on short, axillary peduncles; sepals 5; petals 5, yellow, 3-5 mm. long, attached at the edge of a 10-lobed disk; stamens 10, borne within the disk; style 1, stigma 5-lobed.

Fruit depressed, deeply 5-lobed, separating at maturity into 5 hard, 2-spined segments, the spines 2-6 mm. long, with numerous smaller spines that form a broad, dorsal, longitudinal row.