Astragalus Ravenii

Delicate, diffuse, perennial, with a taproot and subterranean root-crown or shortly forking caudex, strigulose nearly throughout with fine, straight, appressed and a few narrowly ascending hairs up to 0.35—0.55 mm. long, the herbage silvery-cinereous, the leaflets a little more densely and loosely pubescent above than beneath; stems very slender, weak, prostrate, simple, 1.5-10 cm. long, pallid, glabrous and buried for a space of 1—6 cm., the few emersed internodes 2— 12 mm. long; stipules 0.8—1.5 (2) mm. long, the lowest amplexicaul and connate into a loose, campanulate, bidentate, papery, stramineous or brownish sheath, the upper ones firm, herbaceous, sometimes purplish, less strongly connate or almost free; leaves 0.5—2.5 (3) cm. long, slender-petioled, with 7—11 (13) broadly oblong-obovate or suborbicular, retuse, subsessile leaflets (1) 1.5—3.5 (4) mm. long; peduncles filiform, (1) 1.5—5.5 cm. long, mostly far surpassing the leaf; racemes loosely but very shortly (2) 3—6 (8)-flowered, the flowers spreading, the axis scarcely elongating, 1.5—7 mm. long in fruit; bracts ovate or triangular- lanceolate, 0.7—1.5 mm. long; pedicels slender, straight or nearly so, ascending, at anthesis 0.5-1.1 mm., in fruit scarcely thickened and 0.8-2 mm. long, disjointing in age; bracteoles 0; calyx 3.4-4 mm. long, strigulose with white, or white and a few black hairs, the slightly oblique disc 0.7—0.8 mm. deep, the submembranous, campanulate tube 2.5-3.3 mm. long, 2.2-2.5 mm. in diameter, the firm, subulate or triangular-subulate teeth 0.6-1.2 mm. long, the whole becoming papery, ruptured, marcescent; petals whitish, the banner faintly lilac-veined, the keel-tip faintly maculate; banner abruptly recurved through 80-90°, broadly ovate-cuneate, deeply notched, (5.5) 6-8.4 mm. long, 5-6.8 mm. wide; wings 6-7.7 mm. long, the claws 2.1-2.4 mm., the oblanceolate or obovate, obtuse or obscurely erose-emarginate blades 4.3-6 mm. long, 1.7-3.5 mm. wide, the one (usually the right) nearly erect, the other abruptly incurved from the claw and its inner margin infolded; keel 4.5—5.5 mm. long, the claws 1.9—2.2 mm., the nearly half-circular blades 2.7—3.4 mm. long, 2—2.2 mm. wide, incurved through 100-120° to the blunt apex; anthers 0.45-0.5 mm. long; pod ascending (humistrate), tardily deciduous, obliquely ovoid, gently incurved, 8-13 (17) mm. long, 5-8.5 mm. in diameter, moderately inflated but scarcely bladdery, obtuse at base, contracted distally into a short, deltoid, laterally compressed beak, otherwise obcompressed, carinate ventrally by the nearly straight to gently concave suture, low-convex dorsally, the thin, mottled, sparsely strigulose valves becoming papery, delicately reticulate, inflexed as an incomplete septum 0.3-1 mm. wide; dehiscence apical and downward through the ventral suture; ovules 16-20; seeds ocher-brown, sometimes purple-speckled, smooth but dull, 1.8-2 mm. long.— Collections: 3 (o); representative: Mary DeDecker 428 (RSA), in September, 1959 (NY).

Gravelly flats and slopes, 11,250-11,350 feet, on metamorphosed sedimentary and volcanic bedrock, near the crest of the Sierra Nevada in eastern Fresno (and probably adjoining Inyo) County, California.—Map No. 134.—July to early September.

Astragalus Ravenii (Peter Hamilton Raven, 1936- ) Barneby in Aliso 4: 131. 1958. —"California: ... on the plateau north of Sawmill Pass, 11,250 ft., Fresno County, July 28, 1956, Peter H. Raven No. 9863 ... "—Holotypus, CAS!

The Raven milk-vetch is delicately fashioned in every way, technically similar to A. monoensis but smaller and frailer, notable for its very slender stems, tiny leaflets, and small, whitish, faintly lilac-veined flowers disposed in loose clusters of two to six or rarely eight together at the end of almost threadlike peduncles. In fine detail its flower is much like that of A. Pulsiferae, but the vesture of the leaves and of the ordinarily smaller, less-incurved, and less-inflated pod is thinner and appressed. Near or above tree line in the southern Sierra Nevada the only astragali at all like A. Ravenii in general appearance are A. lentiginosus var. ineptus, which has free stipules and larger flowers, and A. Whitneyi which has again larger but purple flowers and bladdery and stipitate fruit. A third species with flowers equally small but normally acaulescent is A. platytropis, not recorded from farther south in the Sierra than the Sweetwater Mountains in Mono County, but collected recently in the Inyo Mountains and possibly to be expected in the range of A. Ravenii; in this the petals are of nearly equal length and the greatly swollen pod is fully bilocular. The only known station for A. Ravenii, at Sawmill Pass, lies at a point on the Sierra crest about sixty miles south of the restricted area in Mono County where its closest relative, A. monoensis, is endemic at elevations of about 7500-7900 feet. The species is associated with the Sierra kentrophyta, A. Kentrophyta var. danaus.