Astragalus nuttallianus var. macilentus

(Small) Barneby

Mem. New York Bot. Gard. 13: 1065. 1964.

Common names: Small milkvetch
Endemic
Basionym: Hamosa macilenta Small Fl. S.E. U.S., 618, 1332. 1903
Synonyms: Astragalus macilentus (Small) Cory
Treatment appears in FNA Volume 11.

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.
Stanley L. Welsh +
- Small Barneby +
Hamosa macilenta +
Small milkvetch +
200–1400 m. +
Dry gravelly or rocky sites, disturbed soils. +
Flowering Mar–May. +
Mem. New York Bot. Gard. +
Astragalus macilentus +
Astragalus nuttallianus var. macilentus +
Astragalus nuttallianus +
variety +