Monographs Details: Astragalus humistratus var. crispulus Barneby
Authors:Rupert C. Barneby
Authority: Barneby, Rupert C. 1964. Atlas of North American Astragalus. Mem. New York Bot. Gard. 13(1): 1-596.
Family:Fabaceae
Description:Variety Description - Gray-villous (villosulous) and often subtomentose with extremely fine, curly, ± entangled hairs mixed with others longer, loosely spreading and ascending, the longest up to 1-1.5 mm. long, the leaflets pubescent on both sides, but sometimes more thinly so above; stems prostrate, radiating, freely and divaricately branched, (0.5) 1.5-5.5 dm. long; stipules 2.5-8 mm. long, leaves 1-4.5 (5) cm. long, with 11—15 narrowly lanceolate to ovate, acute or subacute (when broad, obtuse), flat or loosely folded leaflets (2) 3-14 mm. long; peduncles (1) 1.5-3.5 (4) cm. long; racemes (3) 5-12-flowered, the axis (0.5) 1-3 cm. long in fruit; calyx villosulous like the herbage, 4.6-5.5 mm. long, the disc 0.6-0.8 mm. deep, the tube 2.9-4 mm. long, 2-2.7 mm. in diameter, the teeth 1.2-2.4 mm. long; petals whitish, faintly pink-tinged; banner 7-9.2 mm. long, (3) 4—5 mm. wide; wings (0.6, rarely 1.4 mm. shorter to 0.8 mm. longer than the banner) 6.7-8.6 mm. long, the claws 2.5-3.2 mm., the blades 4.6-6.3 mm. long, 1.7-2.4 mm. wide; keel 5.1-6.2 mm. long, the claws 2.5-3.2 mm., the half-obovate blades (2.8) 3-3.7 mm. long, 1.8-2.2 mm. wide, abruptly incurved through 90-100° to the rather sharply deltoid apex; anthers 0.4—0.6 mm. long; pod lunately half-ellipsoid, incurved through ¼-½ -circle, cuneate at base, cuspidate at apex, laterally compressed and obscurely triquetrous, low-convex or shallowly grooved dorsally in the lower half or third, carinate ventrally by the suture, the thinly papery valves strigulose- villosulous with short, sinuous often mixed with a few long, straight hairs; ovules 6-9.

Distribution and Ecology - Dry banks and benches in xeric pine forest, in sandy soils of volcanic origin, 7250-8150 feet, local but forming colonies, known only from the White and San Francisco Mountains on the Little Colorado-Gila watershed, in the southeast comer of Apache County, Arizona, and adjoining Catron County, New Mexico. Map No. 41.—August to September.

Discussion:

Immediately recognized by its villous or villous-tomentulose vesture, var. crispulus differs further from all other forms of the ground-cover milk-vetch in the oblanceolate or narrowly obovate banner, the more nearly obtuse keel, and the pod of uncommonly thin texture and strong lateral compression. The petals are almost clear white when fresh, faintly pink-tinged in age, but lack the infusion of yellowish or luridly purplish coloring otherwise characteristic of A. humistratus. The range of var. crispulus lies within that of var. humistratus; in the White Mountains colonies of the two varieties have been found in close proximity, in one marginally overlapping. So great is the contrast between the two forms as seen gether that one might think them specifically distinct. The link between them is var. humivagans, which extends eastward just into the foothills of the White Mountains and adjoining New Mexico, but generally and probably exclusively at lower elevations. A collection of var. humivagans from Catron County, New Mexico (Datil, Barneby 12,911, CAS, NY, RSA) combines the vesture and broad banner typical of its sort with a small (but pluriovulate) pod nearly resembling that of var. crispulus in form.

The var. crispulus was first collected in 1920, near Greer in the White Mountains, by W. W. Eggleston (NY).

Distribution:Arizona United States of America North America| New Mexico United States of America North America|