Astragalus nuttallianus var. macilentus

Plants strigose-pilosulous, hairs to 0.8 mm. Stems 8–30(–38) cm. Leaves (1.5–)2–9.5 cm; leaf­lets 7–23, blades sometimes dimorphic, distal ones more narrow, linear-elliptic, oblong-oblanceolate, broadly elliptic, or obovate, apex acute or truncate-emarginate. Peduncles 2.5–9 cm. Racemes (2 or)3–27-flowered; axis to (0.5–)1–3 cm in fruit. Flowers: calyx 3.4–5.6 mm, loosely sparsely strigulose-pilosulous, tube 2–3.1 mm, lobes 1.1–3 mm; corolla banner (6.4–)8.5–13 mm; keel apex obtusely rounded. Legumes (10–)13–25 × 1.8–2.7 mm, glabrous; substip­itate. Seeds 12–22.

Phenology: Flowering Mar–May.
Habitat: Dry gravelly or rocky sites, disturbed soils.
Elevation: 200–1400 m.

Distribution

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Tex.

Discussion

Variety macilentus occurs from south-central Texas to the western tip of the state. Species level recognition may be justified because of its elongating inflorescences, substipitate fruits, obtuse keels, and absence of intergradation with sympatric Astragalus nuttallianus (D. Isely 1998). It is easily confused with A. emoryanus in flower, which is distinguished by its sessile and decid­uous fruits.

Selected References

None.

Lower Taxa

None.