Duration: Perennial

Nativity: Native

Lifeform: Forb/Herb

General: Perennial from a short woody caudex, stems erect or ascending, 30-50 cm tall, sparsely strigose, usually more or less purplish; stipules broadly deltoid acute to acuminate 2-5 mm long, scarious, sparsely pubescent to subglabrate.

Leaves: Compound pinnate, 10-12 cm long, ascending, rachis strongly grooved above, leaflets 11-19, obovate to oblong, 2-4 mm wide, 8-25 mm long, rounded to retuse at apex, acute at base, sparsely strigose but green on both surfaces.

Flowers: Peduncles 3-8 cm long, racemes 3-10 cm long, 8-15 flowered, purplish, strigose with white and black hairs; teeth narrowly subulate, 1.5-2 mm long, corollas 6-8 mm long, purplish; banner obovate, slightly exceeding wings, glade of wings slightly longer than claw; keel often ochroleucous, strongly curved, obliquely obovate, rounded at apex.

Fruits: Pods sessile, ovoid, 2.5-4 cm long, 1.5-2 cm wide, stiff hairs, often slightly tinged with purple.

Ecology: Found on plains and mesas; 1,500-7,000 ft (457-2134 m); flowers March-May.

Distribution: s CA, AZ, s CO, NM, s TX; n MEX.

Notes: Astragalus is the most species-rich genus in the world and is especially speciose in the southwest. There are over 200 taxa in Arizona alone. Many species are notoriously difficult so its best to voucher to be sure. This species is a perennial but appearing annual, ranging from small and ground-hugging, to large and straggly; distinguished by having stems which branch above the ground (caulescent); stiff, appressed hairs all over (strigose); leaflet number and width and with more hairs underneath; flowers 6-8 mm long; 1 celled, thin-walled, inflated pods which greatly surpass the calyx which has teeth as long as, or slightly shorter than the tube.

Ethnobotany: Used ceremonially by the Navajo.

Etymology: Astragalus is from Greek astragalos meaning ankle bone and is an early name applied to the genus because of the shape of the seeds, allochrous means of a different color.

Synonyms: None

Editor: SBuckley 2010, FSCoburn 2015

Astragalus allochrous var. allochrous is a prostrate, spreading plant with red stems and small purple flowers. The pods are very inflated and give out a loud pop when crushed. Astragalus allochrous var. allochrous is found at low to middle elevations on hillsides and sandy canyon floor.