Plants mostly 15-45 cm. Leaves: basal rosettes not persistent; basal leaves mostly 2-7 × 0.5-2.5 cm; petioles 1-3 cm; blades oblanceolate, often pinnately lobed; cauline leaves gradually reduced distally. Heads borne singly. Peduncles 3-12 cm. Involucres hemispheric, mostly 5-8 × 7-12 mm Phyllaries mostly 21-34, floccose-tomentose. Rays mostly 20-40; laminae elliptic to obovate, mostly 7-10 × 4-7 mm, apices shallowly 3-toothed. Disc florets mostly 40-50; corollas 3 mm, tubes 0.3 mm, lobes 0.25 mm; style-branch apices acute. Cypselae 3 mm. 2n = 32. Flowering Mar-Nov (depending on rains). Sandy plains and mesas; 100-2000 m; Ariz., Calif., Nev., Utah; Mexico (Baja California, Sonora). Baileya pleniradiata is superficially similar to B. multiradiata and autumnal forms of the latter have often been misidentified as the former (see discussion under B. multiradiata). The two species occasionally occur together or in proximity; hybrids have not been noted. Style appendages readily allow distinction between the two taxa.

Plant: Annual, canescent-tomentose; stems 1-5 dm, branched mostly in basal half Leaves: mostly cauline; basal generally withering by time of flower; basal and lower cauline similar, 2-8 cm, alternate, petioled; blade 1-3 X divided into oblong to ovate lobes; upper cauline sessile, simple, linear to narrowly oblanceolate, generally entire INFLORESCENCE: primary inflorescence a head, each resembling a flower; heads solitary; peduncles 2-10 cm; involucre 7-10 mm diam, hemispheric; phyllaries 20-30, 4-6 mm Flowers: Ray flowers 20-60, in 2 or more series; ligules 6-10 mm, widely elliptic to obovate, ± entire to shallowly 3-lobed, bright yellow, papery, reflexed and persistent on fruit when dry; Disk flowers many; corollas 3 mm, yellow, gland-dotted, lobes triangular, long-hairy; anther tips triangular; style tips short-triangular Fruit: achenes, 3-4 mm, cylindric, distinctly angled; ribs of angles most prominent Misc: Desert roadsides, sandy soils; < 1500 m.; Mar-Jun, Oct-Nov