Gayophytum caesium Torrey &A. Gray; G. helleri Rydberg; G. helleri var. glabrum Munz; G. humile A. Jussieu var. hirtellum Munz; G. racemosum var. caesium (Torrey & A. Gray) Munz; G. ramosissimum Torrey &A. Gray var. pygmeum Jepson

Herbs glabrous or strigillose, rarely villous. Stems erect or spreading, branched mostly proximally, secondary branches few or none, branching not dichotomous, (5–)10–40 cm. Leaves little reduced distally, crowded, 10–25 × 1–3 mm; petiole 0–5 mm; blade narrowly lanceolate or elliptic to sublinear. Inflorescences with flowers arising as proximally as first 1–3 nodes from base. Flowers: sepals 0.8–1.4 mm, reflexed singly or in pairs; petals 1.3–1.8 mm; pollen 90–100% fertile; stigma subglobose, surrounded by anthers at anthesis. Capsules ascending, flattened, 10–15 × 0.8–1.4 mm, not constricted between seeds, valve margins entire or slightly undulate, all valves free from septum after dehiscence, septum straight; pedicel 0.4–2 mm. Seeds (10–)14–34, all developing, arranged obliquely to septum and subopposite seeds in adjacent locule, forming 2 even rows in capsule, light to dark brown, 0.8–1 × 0.3–0.5 mm, glabrous or densely puberulent. 2n = 28.

Flowering May–Oct. Drying margins of meadows and pools; 1000–4000 m; Alta.; Ariz., Calif., Colo., Idaho, Mont., Nev., Oreg., S.Dak., Utah, Wash., Wyo.

Gayophytum racemosum, on the basis of mor­phological and ecological observation, appears to be an allotetraploid derived from hybridization between G. decipiens and G. humile or a related species that is presumably extinct. Gayophytum racemosum is most readily distinguished from G. humile by the dehiscence of the capsules and from G. decipiens by branching habit and by the capsules, which are not as conspicuously flat in G. decipiens.