Monographs Details: Astragalus lentiginosus var. toyabensis Barneby
Authors:Rupert C. Barneby
Authority: Barneby, Rupert C. 1964. Atlas of North American Astragalus. Mem. New York Bot. Gard. 13(2): 597-1188.
Family:Fabaceae
Description:Variety Description - Diffuse or decumbent, the slender stems 1-3 dm. long, the herbage green, thinly strigulose with subappressed hairs up to 0.35-0.6 mm. long, the leaflets glabrous above and often nearly so beneath; leaves 3-13 (16) cm. long, with slender petioles and (7) 15-25 oval-obovate or broadly oblanceolate, obtuse and mucron- ulate or truncate, thin-textured, or (in exposed places) narrowly elliptic-oblanceolate, acute or subacute, thicker-textured, mostly flat leaflets (2) 6-16 (21) ram. long; peduncles usually very slender, 1.5-4.5 (6.5) cm. long; racemes 7-18- flowered, the fruiting axis 1-2.5 (5) cm. long; calyx (6.2) 6.7-10 mm., the tube 5-6.5 mm. long, 2.4-2.8 mm. in diameter, the subulate teeth (1.2) 1.6-3.5 (4) mm. long; petals normally pink-purple, rarely whitish with pale pink keel- and wing-tips; banner 12.6-17 mm. long, 5.6-8 mm. wide; wings (11) 11.8-13.8 (15) mm., the blades 6.3—8.3 mm. long; keel (9) 9.4—12 mm. long, the blades 4-4—6 mm. long, pod narrowly to broadly ovoid-acuminate, more or less strongly inflated, 0.8—2 cm. long, 4—11 mm. in diameter, the incurved, unilocular, triangular-acuminate beak (3) 4-11 mm. long, the papery, usually mottled, glabrous or exceptionally puberulent valves becoming papery and stramineous; ovules 13-20.

Distribution and Ecology - Dry stony hillsides among sagebrush, ascending thence to open treeless crests within and rarely above the timber belt, occasional in cool loamy soils among aspens, mostly on igneous bedrock, (6000) 8000-11,300 feet, locally frequent in the Wassuk, Toiyabe, and Monitor Ranges, westcentral Nevada.-Map No. 130 [Map No. 129]. -June to August.

Discussion:

The var. toyabensis is the first of a series of varieties characterized by flowers of moderate or large size and ordinarily bright purple coloring which are gathered into short racemes elongating little or not at all in fruit. It is evidently closest to var. scorpionis of the preceding group, differing chiefly in its longer flower, with banner 12.6-17 mm., not 8.5-12.2 mm. long. Ordinarily a montane plant, it descends occasionally into the foothills as low as 6000 feet where it enters the habitat of, and apparently passes into, var. araneosus, a form which differs ideally in its leathery or at least much more stiffly papery pod.

At the time of my revision of the freckled milk-vetch (1945) the material available from the mountains of Nevada was inadequate to illustrate the racial realities, and consequently I made several blunders which seem inexcusable today. In the first place I described the typus of var. toyabensis as white-flowered, almost certainly an error, and compared it with var. platyphyllidius, with which it has no especially close ties. From the ample sets of specimens collected by Maguire & Holmgren, J. & M. Linsdale, and others, I have learned that the common montane variety of A. lentiginosus in the volcanic mountains of central and westcentral Nevada is at least normally purple-flowered. In general aspect it resembles the smaller-flowered var. scorpionis endemic to the limestone ranges of eastern Nevada and adjoining Utah, which is dispersed over an almost equally great vertical range and varies in parallel fashion so far as stature and the pod’s inflation and curvature are concerned. At great elevations the plants of both varieties become dwarfed and the pod tends to become little swollen; I wrongly associated this phase of var. toyabensis (op. cit., p. 85) with the fragmentary typus of var. scorpionis, now believed to be identical with what is there described as var. tremuletorum. In the timber belt var. toyabensis becomes a greener, lusher plant, sometimes found in fertile soil among aspens, and I mistook one specimen from this environment for var. tremuletorum (op. cit., p. 86), by unhappy accident the specimen that suggested the varietal epithet.

Distribution:Nevada United States of America North America|