337c. Astragalus calycosus var. mancus
Diminutive in stature (rarely somewhat drawn out in shade); leaves 1.5-3 (4) cm. long with 7-13 oblanceolate, elliptic, or narrowly obovate, obtuse or rarely retuse leaflets 2-6 mm. long, crowded on a rachis 1 (1.3) cm. long or less; peduncles subfiliform, 2-4.5 cm. long; racemes (1) 2-4-flowered; calyx 5-8.5 mm. long, the tube 4-5.5 mm., the teeth 1-3 mm. long; petals whitish, the banner 11-13 mm. long; wings about as long, the terminal lobes 1.4-2.7 mm. long, either naked or minutely appendaged in the sinus (the appendage not over 0.4 mm. long); keel 9-10.2 mm. long.—Collections: 13 (i); representative: Clokey 5516 (CAS, NA, NY, OB, RSA, SMU, WIS, WS); Maguire & Holmgren 21,885 (NY, WS, WTU), 22,076 (NY, WTU), 25,816 (NY, RSA); Cottam 3310 (POM).
Barren rocky ridges at or near the limit of trees, descending on open slopes into clearings of yellow pine forest, commonly but not quite exclusively on limestone, (7700) 8400-13,000 feet, scattered in the higher mountain ranges of Nevada (Charleston and Sheep Ranges, Clark County; Toquima Range, Nye County; Ruby Mountains, Elko County; Mount Wheeler, White Pine County) and adjoining Utah (Deep Creek Range, Juab County).—Map No. 154.—May to August.
Astragalus calycosus var. mancus (Rydb.) Barneby in Leafl. West. Bot. 7: 195. 1954, based on Hamosa manca (defective, the allusion not explained) Rydb. in Bull. Torr. Club 54: 17. 1927.—"Clover Mountains, near Deeth [err. "Death"], Nevada, July 24, 1908, Heller 9163; apparently also in the Charleston Mountains, Clark County, Heller 11032."—Holotypus (A. A. Heller 9163), NY! isotypi, NA, US!—Astragalus mancus (Rydb.) Wheeler in Rhodora 40: 136. 1938.
Taking into account the degree of variation already noted in var. calycosus, one might logically interpret Hamosa manca as no more than a montane ecotype of its species, and such it may prove to be. However, the existence of two well-differentiated forms of the Torrey milk- vetch is impressively demonstrated on the east slope of the Charleston Mountains. In this industriously botanized range of mountains, where intermediates between var. calycosus and var. mancus should, if they exist, already have come to light, the typical form of the species is known to occupy a belt between 6000 and 7400 feet elevation in the piñon-juniper forest, whereas var. mancus first appears in the ponderosa pine forest at about 8500 feet and has been traced upward to timber line. Elsewhere the two varieties are not so clearly divided by life- zone. A collection from 11,000 feet in the Toiyabe Range (Stewart Creek, Maguire & Holmgren 25,927, RSA), although suggestive of var. mancus in its slender habit, has leaflets too large and too few for the present variety and is technically inseparable from var. calycosus, which rarely extends elsewhere above the 8000 foot contour. It should be emphasized that short calyx-teeth ("deltoid, 1 mm. long," Rydb., ex char.; "1-1.5 mm. long," Clokey, 1942, p. 213) no longer serve as a reliable criterion for var. mancus.
In the Charleston Mountains the wing-petals of var. mancus are minutely appendaged in the apical sinus; those of var. calycosus are simply notched. Farther north, where var. calycosus is appendaged, it is var. mancus (at least in the Toquima Range and the type-locality) that has naked sinuses.