Annuals (sometimes persisting), 2-60 cm (delicate or robust, stems relatively few to many, erect or spreading); puberulent to hirsute, glandular-pubescent. Leaves: petioles 3-45 mm; blades ovate, cordate, suborbiculate, or triangular, 17-60 × 10-50 mm, margins deeply toothed, lobed, cleft, or divided, lobes indented to irregularly dissected. Heads borne singly or in corymbiform arrays, 4-10 × 4-10 mm. Peduncles 1-70 mm. Involucres campanulate to hemispheric. Phyllaries 10-20, lanceolate or oblanceolate to ovate-lanceolate, 4-6 × 1-2 mm. Ray florets usually 8-14, rarely rudimentary or 0; corollas white, laminae oblong, 1-4(-6) × 1-3 mm. Disc florets 40-100+; corollas yellow, tubes 0.7-1.3 mm, throats tubular to tubular-funnelform, 0.8-1.3 mm, lobes 0.1-0.2 mm. Cypselae suboblong, oblanceolate, or subcuneate, (1.5-)2-3 mm, margins thin (not calloused), long- or short-ciliate; pappi 0 or of 1 antrorsely to retrorsely barbellate bristles 1-3 mm plus crowns of hyaline, laciniate scales. 2n = 65-72 or 100-116. Flowering year round (depending on latitude). Coastal bluffs, desert plains, slopes, washes; 10-1500 m; Ariz., Calif., Nev., Utah; Mexico; South America (Chile, Peru). Perityle emoryi is a widespread polyploid of diverse habitats and is often weedy. It is variable; none of the variation appears to have population significance and does not require taxonomic recognition. The range of P. emoryi appears to be gradually expanding.

Plant: Annual 2-60 cm, puberulent to rough-hairy and glandular; stems simple to much-branched Leaves: generally alternate, petioled; blades 2-10 cm, ovate, round, or triangular, coarsely toothed to palmately lobed, teeth and lobes generally again toothed or lobed INFLORESCENCE: primary inflorescence a head, each resembling a flower; heads radiate (rarely disciform), 1-many; peduncles 0.1-7 cm; involucre hemispheric to bell-shaped; phyllaries many, 5-6 mm, lanceolate or oblanceolate to ovate Flowers: Ray flowers generally 8-12; ligules 1.5-4 mm, white, rarely vestigial; Disk flowers: many; corollas 2-2.5 mm, yellow, 4-lobed; anther tips triangular; style tips tapered Fruit: achenes, generally 2-3 mm, linear to oblanceolate, very flat; margins thin, ciliate; surfaces of ray achenes generally ± puberulent; surfaces of disk achenes generally glabrous; pappus scales well developed or vestigial, bristle 0 or 1, 1-2.5 mm Misc: Desert plains, slopes, and washes; < 1000 m.; Feb-Jun References: J.C. Hickman, ed. The Jepson Manual.W.B. McDougal. Seed plants of Northern Arizona. ASU specimens.