Plants tuft-forming, acaulescent to subacaulescent, 2–10 cm, stri­gose to strigulose, hairs mal­pighian; from superficial cau­dex. Stems prostrate or reduced to sessile crowns, 0–6 cm, internodes mostly obscured by stipules, strigose to strigulose. Leaves 2–10 cm; stipules 2–7 mm, submembranous becoming papery; leaf­lets (1–)5–17, blades obovate to oblanceolate, (2–)4–15 mm, apex obtuse to truncate or emarginate, surfaces strigose. Peduncles incurved-ascending, 1–8 cm. Racemes 2–11-flowered, flowers spreading-ascending; axis (0.3–)1–2 cm in fruit; bracts 2–5 mm; bracteoles 0(–2). Pedicels 1–3.5 mm. Flowers 17–24(–25.5) mm; calyx cylindric, 9–13 mm, strigulose, tube 6.5–9.5(–12) mm, lobes subulate, 1.5–3 mm; corolla ochroleucous or tinged purplish to pink-purple; banner recurved through 45°; keel 14.6–20(–22) mm. Legumes ascending (humistrate), purple-mottled, definitely incurved, oblong-ovoid or ellipsoid, 20–40(–45) × 7–16 mm, unilocular, contracted into distinct, conic-cuspidate beak, fleshy becoming alveolate-spongy, walls 1+ mm thick, exocarp and endocarp separated by thick, pulpy mesocarp, strigose. Seeds 37–60. 2n = 22.

Phenology: Flowering late Apr–Jul.
Habitat: Juniper-pinyon, sagebrush, mixed desert shrub, and grassland communities.
Elevation: 1500–2400 m.

Distribution

• Generated Map
• Legacy Map

Colo., Mont., Utah, Wyo.

Discussion

Astragalus chamaeleuce is known from western Colorado from Montrose County northward, the Uinta Basin southward to Emery and Grand counties in Utah, southwestern to north-central Wyoming, and Carbon County in Montana.

The thick-walled but relatively light-weight fruits of Astragalus chamaeleuce have a spongy, thickened meso­carp that exfoliates with the exocarp at maturity. The fruits are windblown after separation from racemes.

Selected References

None.

Lower Taxa

None.