Centrostegia thurberi

Plants 0.3-2(-3) × (0.6-)1-4(-5) dm. Leaf blades (0.5-)1-3.5(-4) × 0.3-0.8(-1) cm. Inflorescences: bracts mostly spreading, (1-)2-6(-10) mm; awns 1-2 mm. Involucres (2-)3-6(-8) mm; basal spurs with awns 0.2-2 mm; teeth flattened and keeled distally, awn erect, short, 0.3-1 mm. Flowers: perianth 2-3(-3.5) mm; tepals oblanceolate; filaments 1-3 mm; anthers 0.4-0.5 mm. Achenes 2-2.5 mm. 2n = 38.

Flowering Mar-Jul. Sandy to gravelly flats and slopes, mixed grassland, saltbush, creosote bush, and chaparral communities, pine-oak and montane conifer woodlands; 300-2400 m; Ariz., Calif., Nev., Utah; Mexico (Baja California, Sonora).

Centrostegia thurberi is fairly consistent morphologically throughout its range except for individuals in some populations in the mountains of the southern Coast Ranges that tend to have slightly longer and more robust involucres. The name var. macrotheca is available for such plants.