Mem. Amer. Acad. Arts, n. s. 4: 65. 1849.
Subshrubs or shrubs, (8–)20–45(–120+)[–300] cm. Stems erect [decumbent], branched from bases and/or ± throughout. Leaves cauline; opposite [alternate]; sessile; blades 1(–3)-nerved, narrowly elliptic or oblanceolate to linear, faces glabrate or puberulent, gland-dotted (in pits). Heads discoid, usually borne singly or in pairs [in ± cymiform arrays]. Involucres cylindric [turbinate], [2–]3–5 mm diam. Phyllaries persistent (at least outer), 8–12+ in 3–4+ series, not notably nerved, deltate-ovate to oblong, lanceolate, or linear, unequal. Receptacles flat to slightly convex (glabrous), epaleate [partially paleate]. Florets 3–4[–6+]; corollas white or pink to purple, throats narrowly funnelform (sometimes puberulent inside), lobes 5, narrowly triangular to linear (adaxially densely papillose); styles: bases enlarged, glabrous, branches ± filiform (appendages cylindric or slightly flattened, densely papillose). Cypselae subcylindric, [4–]8–10-ribbed, ± hirtellous; pappi persistent, of 0–5+ muticous, erose, lacerate, or lanceolate to subulate scales (1–4 mm) plus [5–]9–12+ aristate scales (10–15 mm) [coroniform]. x = 11, 12.
sw United States, Mexico.
Species 7 (1 in the flora).