Proc. Amer. Acad. Arts 24: 54. 1889
Annuals, 10–40 cm. Stems erect, much branched. Leaves basal and cauline; mostly alternate (proximal opposite); mostly sessile; blades 1-nerved, linear, margins entire, faces glabrous or puberulent, sometimes gland-dotted. Heads discoid, in loose, corymbiform arrays or borne singly. Involucres ± campanulate to obconic, 5–6 mm diam. Phyllaries persistent, 20–30+ in 3–4+ series, not strongly nerved, lanceolate, unequal (± chartaceous, margins scarious). Receptacles flat, epaleate. Florets 20–30; corollas white, throats cylindric or narrowly urceolate (lengths 5–6 times diams.); styles: bases not enlarged, glabrous, branches filiform-clavate. Cypselae fusiform, 5-ribbed, scabrellous on ribs; pappi persistent, of 3 muticous scales plus 3,aristate scales. x = 10.
w United States, nw Mexico.