Hist. Pl. 4: 344. 1873.
Plants subshrubs, perennial, 10–40 cm, from ligneous rhizome. Stems 1–20, clustered, erect, simple or branched from proximal nodes, glabrous or strigose to pilose. Leaves: proximal opposite or subopposite, distal usually alternate, petiolate or sessile; stipules linear-subulate and minute to leaflike, 3–40 mm, glabrous or hirsute, gland-tipped; petiole 0–1 mm; blade linear, narrowly elliptic, lanceolate, or oblanceolate, 1–5.5(–6) × 0.1–0.8(–1.1) cm, base attenuate, margins usually entire, ciliate or eciliate, apex acute to acuminate, surfaces glabrous, strigose, or pilose. Inflorescences 1-flowered; peduncle usually pendant at anthesis, sometimes horizontal or erect, usually pendant in fruit, 3–14 mm, hirsute to densely puberulent, occasionally glabrous on segment distal to joint; bracteoles present. Flowers: sepals appressed to corolla, ovate to lanceolate, margins ciliate or eciliate, apex acute; petals: upper greenish white, cream, or yellowish, with purple tips, oblong, 2–2.5 mm, apex acute to rounded, glabrous; laterals similar to upper except 3 mm; lowest greenish white, cream, or yellowish, sometimes tinged purplish, 2.5–6 mm, claw 2–3 × 0.5 mm, distal limb broadly ovate to orbiculate, ± concave at anthesis, 1–3 mm wide, apex rounded to obtusely angled, adaxial surface usually bearded basally and on claw; presence of cleistogamous flowers not determined. Capsules ovoid to globose, 4–7 mm. Seeds 6, dark brown to shiny black, subglobose, ± flattened with angular edges, or broadly ovoid, 1.8–2.5(–3) mm. 2n = 16, 24, 32.
Phenology: Flowering Apr–Oct.
Habitat: Dry plains, gravelly soil in prairies, mesas, fields, desert grasslands, pinyon-juniper woodlands, chaparral, rocky slopes, forest edges, oak and mesquite savannahs, riparian habitats
Elevation: 10–2100 m
Ariz., Colo., Kans., N.Mex., Okla., Tex., Mexico (Chihuahua, Coahuila, Sonora).