Plants mostly 20-75 cm. Leaves: basal leaves (not persistent) mostly 5-12 × 0.5-1 cm; petioles often in-distinct; blades linear-oblanceolate to oblanceolate, sometimes pinnately lobed; cauline leaves linear, seldom lobed, often not reduced distally. Heads in loose, cymiform arrays. Peduncles 2-5 cm. Involucres campanulate, mostly 5-8 × 5-8 mm. Phyllaries mostly 8-13, floccose-tomentose. Rays mostly 5-7; laminae elliptic to ovate, mostly 5-8 × 4-6 mm, apices shallowly to indistinctly 3-toothed. Disc florets mostly 10-20; corollas 2.5-3 mm, tubes 0.4 mm, lobes 0.25 mm; style-branch apices truncate. Cypselae 3 mm. 2n = 32. Flowering Mar-May. Sandy soils, deserts; 60-700 m; Ariz., Calif.; Mexico (Baja California, Sonora). The most distinct species of the genus, Baileya pauciradiata has the most limited distribution and is, perhaps, the least abundant.

Baileya pauciradiata also possesses cytotoxic sesquiterpene lactones, namely odoratin and paucin (J. J. Hoffmann et al. 1978).

Baileya pauciradiata is connected to the moth Schinia pallicincta Smith, which is closely related to the species of noctuid moth that inhabits B. multiradiata. Schinia pallicincta occupies mostly sand dunes of southern California and uses B. pauciradiata as a primary feeding source (T. G. Myles and B. F. Binder 1990).

Baileya pauciradiata has occasionally been found growing with or near B. pleniradiata; natural hybrids between them have not been recorded, nor have synthetic crosses been successful (R. C. Brown 1974). Brown supported the genetic isolation of the species from the other taxa by demonstrating complete barriers to gene exchange.

Plant: Annual (rarely perennial herb), ± loosely tomentose; Stems 1-5 dm, generally branched above base Leaves: alternate, simple, mostly cauline; basal soon withering; cauline leaves 4-14 cm, not markedly reduced upward, linear-oblong to lanceolate or oblanceolate, entire or divided into linear lobes INFLORESCENCE: primary inflorescence a head, each resembling a flower; heads 2-3 in cymes; peduncles 2-5 cm; involucre 4-6 mm diam, cylindric to bell-shaped; phyllaries 8-10, 4-6 mm Flowers: Ray flowers 4-8; ligules 4-10 mm, obovate, shallowly 3-lobed, pale yellow, sessile on ovary, papery, reflexed and persistent on fruit when dry; Disk flowers 8-20; corolla 2.5-3 mm, yellow, gland-dotted, lobes triangular, long-hairy; anther tips triangular; style tips short-triangular Fruit: 4-5 mm, narrowly club-shaped, evenly ribbed, short-rough hairy and gland-dotted to glabrous; pappus 0 Misc: Sandy desert soils, especially dunes; Feb-Jun, Oct