Herbs. Stems usually prostrate or twining, rarely subascending, puberulent to strigulose or villosulous, hairs silvery. Leaves trifoliolate; stipules persistent, linear or linear-lanceolate, 1.5–3 × 0.5 mm, acute to acuminate; petiole 5–35 mm, puberulous, strigulose, or villosulous; leaflet blades lanceolate-ovate, 5–45 × 20–25 mm, leathery, gland-dotted, base obtuse or subcordate, margins revolute, apex acute or obtuse, surfaces puberulent, strigulose, or villosulous. Inflorescences 1(2 or 3) simple flowers per axil, shorter than leaves, 0.6–1.5 cm. Pedicels 1–6 mm. Flowers: calyx 3–5 mm, villous or villosulous, tube 1.5–2.5 mm, lobes subulate, laterals 1–3.5 mm, lengths to 2.5 times tube, adaxials 0.5–2 mm; corolla yellow, veined brown; banner widely ovate, 5–7 × 3.5–5 mm, apex emarginate, puberulent; wings oblong to ovate, 5–6 × 1–2 mm, glabrous; keel 5–6.5 × 2–2.5 mm, glabrous; stamens 4–6 mm. Legumes oblong, compressed, 15–25 × 4–6 mm, puberulent-hirtellous, hairs intermixed. Seeds brown, black or mottled, subglobose, compressed, 3–4 × 3–4 mm. 2n = 22.

Phenology: Flowering spring–summer.
Habitat: Dry limestone, sandy or igneous soils, grasslands, canyons, mountain slopes, roadsides, forest clearings.
Elevation: 40–2700 m.

Distribution

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Ariz., N.Mex., Tex., Mexico (Chiapas, Chihuahua, Coahuila, Durango, Nuevo León, Puebla, San Luis Potosí, Sonora, Tamaulipas, Veracruz), South America.

Discussion

Rhynchosia angustifolia Engelmann ex A. Gray is an illegitimate name that pertains here. Dolicholus texensis Vail and its var. angustifolius (A. Gray) Vail are illegiti­mate and superfluous names that also pertain here.

Selected References

None.

Lower Taxa

None.