Herbs, multistemmed, 0.3–3 (–3.5) dm (rarely straggling to 10 dm). Stems decumbent to erect, usually pubescent, rarely glabrous, hairs spreading or incurved. Leaves subsessile to petiolate, petiole to 1 (–1.5) mm; blade elliptic to linear, lanceolate, ovate, obovate, or scalelike, (3–) 4–41 × (0.5–) 1–12 (–18) mm, base rounded to cuneate, apex obtuse to rounded, surfaces pubescent or glabrous, hairs incurved or spreading. Racemes terminal, usually leaf-opposed, often also from near base of plant, these usually with chasmogamous flowers, occasionally bearing reduced, beakless cleistogamous or semi-cleistogamous flowers, rarely with cleistogamous or semi-cleistogamous flowers throughout, 1–12 (–15) × 0.3–1.5 cm; rachis not thorn-tipped; peduncle 0–1 cm; bracts usually persistent, ovate, lanceolate, or elliptic. Pedicels 1–4.5 mm, pubescent. Flowers usually pink to purple, rarely white, keel yellowish distally, wings pink or rose, (3.7–) 4–7.4 (–7.7) mm; upper sepal persistent, other sepals deciduous, upper sepal ovate, 1.7–4.5 (–5.2) mm, lower sepals lanceolate to obovate, (1.3–) 1.6–3.5 (–3.8) mm, pubescent or glabrous; wings obovate to oblong-obovate, 3–6.4 (–7.2) × (1.2–) 1.4–3.2 mm, glabrous or pubescent; keel (2.7–) 3.1–6.2 mm, sac glabrous or with scattered hairs, beak linear (or bluntly rounded), (0–) 0.5–2 × (0–) 0.2–0.6 mm, glabrous or pubescent. Capsules ellipsoid, oblong, slightly ovoid, or obovoid, 3.3–6 (–6.8) × 2–4 mm, base rounded to subtruncate, often oblique, margins with narrow wing or not winged, usually pubescent, rarely subglabrous. Seeds 2.8–4.3 mm, pubescent; aril 0.7–2.5 mm, lobes to 3/4 length of seed.

Distribution

sw, sc United States, n Mexico

Discussion

Varieties 3 (2 in the flora).

Variety eucosma (S. F. Blake) T. Wendt is known from northern Mexico.

Selected References

None.

Lower Taxa

Rhinotropis lindheimeri var. lindheimeri, Rhinotropis lindheimeri var. parvifolia

Key

1	Stems usually with spreading hairs, hairs rarely somewhat crisped, mostly 0.3–0.5 mm; leaf blades usually elliptic, ovate, or obovate proximally, distally becoming narrowly so, venation usually prominently reticulate, surfaces pubescent (not glabrous); keel sacs glabrous or with scattered, spreading hairs proximally, hairs not incurved in distal 1/2.	Rhinotropis lindheimeri var. lindheimeri
1	Stems usually with incurved hairs, hairs rarely irregularly spreading, 0.07–0.15 mm, rarely glabrous; leaf blades lanceolate, linear, or scalelike to elliptic, ovate, or obovate, venation usually not prominently reticulate (usually midvein prominent abaxially, occasionally reticulate), surfaces pubescent or glabrous; keel sacs glabrous or, rarely, with incurved hairs in distal 1/2.	Rhinotropis lindheimeri var. parvifolia