Smithsonian Contr. Knowl. 5(6): 104, plate 14. 1853.
Annuals, 5–30 cm; taprooted. Stems 1–3, erect or ascending, branched from bases; distal stems, branches, and involucres conspicuously dotted with short, stipitate, flat-topped glands that resemble tacks. Leaves basal and cauline; alternate; sessile; basal blades pinnately lobed (lobes narrow, linear, often delicate, spreading, margins entire, smooth); distal reduced to linear, entire bracts. Heads borne singly or in open, cymiform arrays. Peduncles (1–3 cm) not inflated, not bracteate. Calyculi of 8–16, reflexed, unequal bractlets (lengths to 1/2 phyllaries). Involucres campanulate, 5–12+ mm diam. Phyllaries 12–20 in 1 series, linear-lanceolate, equal, margins scarious, apices acute. Receptacles flat, smooth, bristly, epaleate (each floret subtended by 1 fine, capillary bristle). Florets ca. 25; corollas white or yellow (showy). Cypselae tan to brown, fusiform, beaked, ribs 5, separated by longitudinal grooves, faces glabrous or scabridulous; pappi (borne on denticulate cups at beak tips) falling (together), of 50–60+, white, basally connate, smooth bristles 5–8(–9) mm in 1 series. x = 7.
sw United States, nw Mexico.
Species 2 (2 in the flora).