Astragalus Casei

Usually slender, somewhat wiry, with subterranean root-crown or shortly forking caudex (sometimes accidentally exposed by weathering), strigulose throughout with straight, filiform or flattened hairs up to 0.4-0.6 mm. long, the stems and herbage greenish or cinereous, the leaflets either equally pubescent on both sides or more densely so and canescent above; stems few or several, erect, or diffuse and ascending, (1)1.5-4 dm. long, simple and leafless at base, divaricately branched or spurred at 1-4 nodes preceding the first peduncle, becoming stiff and zigzag distally; stipules (1) 2-5 mm. long, those at the buried and the first emersed nodes membranous, ovate, ± adnate to the suppressed or vestigial petiole, semi- or fully amplexicaul-decurrent, the upper ones herbaceous, cauline, with deltoid or triangular-acuminate, squarrose or deflexed blades; leaves 3-10 cm. long, shortly petioled, with (5) 9-15 rather distant, elliptic-oblong, oblanceolate, or linear, obtuse, retuse, rarely subacute, flat or folded leaflets 3-25 mm. long, all jointed to the rigid, tapering rachis; peduncles strictly erect or divaricate, 3-9 (12) cm. long, either longer or shorter than the leaf; racemes loosely (5) 8-20 (26)-flowered, the flowers at first ascending, declined in age, the axis elongating, (1.5) 3-12 (17) cm. long in fruit; bracts membranous, rarely green and firm, ovate or lanceolate, 2-3.5 (5) mm. long; pedicels at anthesis ascending, 1-1.8 mm. long, in fruit much thickened, recurved, 1.5-2.3 mm. long; bracteoles usually 2, sometimes up to 1 mm. long, rarely 0; calyx (5.8) 7.5-9 mm. long, strigulose with black, rarely white and a few black hairs, the subsymmetric disc 0.9-1.5 (2) mm. deep, the membranous, pallid or purplish, cylindric or exceptionally deep-campanulate tube (4.6) 5.8-7.5 mm. long, 2-3.5 mm. in diameter, rounded or more commonly tapering and turbinate at base, the subulate or triangular-subulate teeth 1.2-1.8 mm. long, the whole becoming hyaline, ruptured, marcescent; petals pink-purple with white wing-tips, rarely all white; banner varying from oblanceolate to broadly rhombic- obovate, shallowly notched, (12) 13.5-18 mm. long, 5.2-9.5 mm. wide; wings 11.3-15.5 mm. long, the claws 5.7-8.4 mm., the oblong-oblanceolate or narrowly oblong, obtuse, nearly straight blades 6.1-9 mm. long, 1.8-2.4 mm. wide; keel 10.6—13.3 mm. long, the claws 6—7.6 mm., the broadly lunate blades (4.6) 5-6.2 mm. long, 2.3-2.8 mm. wide, gently incurved through 80-95° to the rounded apex; anthers 0.55-0.75 (0.8) mm. long; pod deflexed, sessile, lance- or oblong- ellipsoid, 2—5.5 cm. long, (5) 6—10 mm. in diameter, commonly a little sigmoidally arched (decurved proximally and incurved distally) but sometimes straight or gently incurved its whole length, rounded or obtusely cuneate at base, gradually or abruptly contracted upward into a long-acuminate or shorter and triangular, laterally compressed, rigidly cuspidate beak, elsewhere obcompressed, the ventral face usually low-convex and obtusely carinate by the salient, cordlike suture (but this, especially in strongly incurved pods, depressed and lying in a groove), the dorsal face either flattened or shallowly concave, the lateral angles rather narrow but obtuse, the fleshy, red- or brownish-mottled, strigulose valves becoming stiffly leathery, stramineous or brownish, transversely rugulose-reticulate, not inflexed; dehiscence apical, basal, and through the ventral suture; ovules 32-42; seeds brown, smooth or punctate, dull, 2.4—2.9 mm. long.—Collections: 26 (v); representative: Maguire & Holmgren 25,241 (ID, NY, SMU, RSA, UTC, WS); Eastwood & Howell 9539, 9557 (CAS); Ripley & Barneby 5890 (CAS, RSA); Munz 11,789 (CAS, POM).

Dry hillsides and valley floors, in alkaline gravelly soils overlying granite or basaltic bedrock, commonly in open places among sagebrush or in piñon-juniper forest, rarely on dunes, 4000-8000 feet, locally plentiful and rather frequent in Inyo and Mono Counties, California, from the Panamint Mountains north through Owens Valley to Mono Lake, and in western Nevada from Death Valley north, becoming local northward, to Pyramid Lake and the lower Humboldt River in Washoe and Pershing Counties.—Map No. 108.—April to June.

Astragalus Casei (Eliphalet Lewis Case, 1843-1925) Gray, Bot. Calif. 1: 154. 1876.— "High plateau near Pyramid Lake, N. W. Nevada, Lemmon and E. L. Case."—Holotypus, collected in 1875, GH! isotypus, US! presumed isotypi, labeled "California, Lemmon in 1875," NY (2 sheets)!—Tragacantha Casei (Gray) O. Kze., Rev. Gen. 943. 1891. Xylophacos Casei (Gray) Rydb. in Bull. Torr. Club 52: 147. 1925.

In its area of dispersal the Case milk-vetch is easily recognized by its basally buried stems which branch upward and become stiff and zigzag distally, by its loose racemes of ascending, parti-colored flowers, and by the reflexed, handsomely mottled, unilocular pods of fleshy, ultimately leathery texture. Flowering specimens have sometimes been confused with the sympatric A. Serenoi, but this has few (5-11) longer, acute or mucronulate leaflets and a glabrous ovary. The pod of A. Casei is deciduous and opens after falling, while that of A. Serenoi persists on the raceme and can often be found the following spring attached to withered stems of the preceding season. The petals of A. Casei are normally pink-purple with contrasting white or pallid wing-tips, but albino mutants have been collected in the Panamints (Dearing 3188, SBM) and observed in quantity in Owens Valley. The pod varies greatly in length and in the development of the beak, which may be broadly deltoid or greatly drawn out into a triangular- acuminate point. As a rule the shorter pods are slightly and evenly incurved their whole length, whereas longer ones are gently sigmoid in profile, decurved out of the calyx and turning inward toward the beak.

In California the Case milk-vetch extends no farther south than Death Valley, Rydberg’s record (1925, p. 148) from the San Bernardino Mountains being based on misidentification of an isotypus of A. bicristatus var. tetrapteroides. The plant from eastern Washington (Brandegee 720) identified as X. Casei by Rydberg (l.c.) represents the quite different A. (Argophylli) columbianus.