Leaves: margins sometimes ciliate, faces glabrous, scabrous, or hirsute, midribs sometimes bristly. Paleae often exserted, apices ± attenuate, spine-tipped. 2n = 18, 20.

Flowering Apr-Nov. Open, ± alkaline flats, depressions, waterway banks and beds, in grasslands, saltbush scrub, disturbed sites (e.g., fallow fields); 0-1200(-1800) m; Ariz., Calif., Idaho, Nev., N.Y., Oreg., Wash.; Mexico (Baja California).

Subspecies pungens is circumscribed broadly to include subsp. maritima and subsp. septentrionalis based on morphologic and molecular data (B. G. Baldwin, unpubl.). As treated here, Centromadia pungens subsp. pungens occurs widely in central and northern California, and it is putatively introduced in southwestern California and outside the state.

Plant: Annual 1-12 dm, aromatic; branches generally stiff, bristly

Leaves: generally cauline, alternate; lower 5-15 cm, linear-lanceolate, deeply 2 X divided; upper linear, spine-tipped, glabrous to scabrous, margin stiff-ciliate, generally with axillary leaf clusters

INFLORESCENCE: primary inflorescence a head, each resembling a flower; heads ± clustered; involucre 3-6 mm, generally overtopped by upper leaves; phyllaries keeled, spine-tipped, scabrous; chaff scales scattered, generally spine-tipped

Flowers: Ray flowers many; ligule 3-5 mm, 2-lobed, yellow; Disk flowers many, generally staminate; corollas and anthers yellow; anther tips ovate; style branches long, tips bristly

Fruit: achenes, ± 2 mm, beaked; ray achenes ± 3-angled; pappus 0; disk achenes cylindric or obconic, disk pappus 0

Misc: Grassland, depressions, marshes; < 500 m.