Madroño 47: 204. 2001.
Annuals, 10–50 (–100) cm. Stems erect, strictly branched. Leaves cauline; mostly alternate; petiolate; blades deltate or ovate to lanceolate, 1–3-pinnately lobed (lobes oblong to lance-linear), ultimate margins entire or toothed, faces ± scabrellous and/or hispid, usually glanddotted. Heads ± disciform, usually in loose, (± bracteate or ebracteate) paniculiform arrays (sometimes 3–6+ distal to axil of each bract). Involucres ± hemispheric, 4–5 mm diam. Phyllaries persistent, 10–12+ in 2+ series, distinct, outer 5 herbaceous, inner scarious to membranous. Receptacles hemispheric; paleae spatulate to linear, membranous, sparsely hairy or glabrate, usually glanddotted. Pistillate florets 5–10; corollas 0. Functionally staminate florets 5–10+; corollas whitish, funnelform, lobes 5, soon reflexed (filaments ± connate, anthers weakly coherent or distinct). Cypselae pyriform, ± obcompressed, finely striate, glabrous, little, if at all, glanddotted; pappi 0. x = 18.
sw United States, n Mexico