Annuals, biennials, or perennials, 10-40 cm; fibrous-rooted. Stems erect to ascending (commonly decumbent-ascending and rhizome like), densely white-pannose. Leaves basal and cauline, basal usually withering before flowering, blades spatulate to oblanceolate, 2-5 cm × 6-12(-35) mm (little smaller distally), faces bicolor, abaxial white-pannose, adaxial sparsely to densely arachnose-tomentose. Heads in usually continuous, rarely interrupted (proximally), cylindric arrays 1-6(-8+) cm × 12-18 mm (pressed). Involucres campanulo-urceolate, 4.5-5 mm, bases sparsely arachnose. Phyllaries in 4-6 series, outer (brown or greenish brown) broadly ovate-triangular, lengths ca. ¹/2 inner, apices acute to acute-acuminate (mid phyllaries ± keeled near apices), inner oblong, laminae usually dark brown, sometimes purplish (at stereome-lamina junction), apices rounded to obtuse, apiculate. Florets: bisexual (3-)4-6; all corollas usually yellowish, sometimes purplish distally. Cypselae (tan to brownish) 0.7-0.8 mm.

Flowering Apr-Jul(-Oct). Mostly coastal and near-coastal sites, dunes, ocean bluffs, sandy fields, and roadsides, clay-loam, roadcuts, ditches, cliffs, pine woods, chaparral slopes, tidal marsh edges; 0-700(-1100) m; B.C.; Calif., Oreg., Wash.

Gamochaeta ustulata usually has been included in G. purpurea; it differs mostly in its longer duration, thicker and shorter stems, larger, more compact arrays of larger, brown heads, and aspects of phyllary morphology.