Astragalus lentiginosus var. albifolius

Perennial, slender but often vigorous, densely strigulose throughout or nearly so with appressed or subappressed hairs up to 0.35-0.65 mm. long, the herbage cinereous or slivery, the leaflets nearly always more densely pubescent above than beneath; stems prostrate or scrambling up through low shrubs, (1) 3-10 dm. long, simple or commonly divaricately branched at 1-6 nodes preceding the first peduncle, floriferous upward from up to 6—20 successive axils, flexuous or abruptly zigzag distally; leaves 2—9 cm. long, the upper ones subsessile and divaricate or recurved, the median ones often shorter than the internodes, with (9) 11-17 (21) oblanceolate, elliptic, or narrowly oblong, obtuse or subacute, mostly folded leaflets (3) 5-15 (18) mm. long; peduncles divaricate or ascending at a wide angle, (1) 1.5—6.5 cm. long; racemes (9) 12—35-flowered, at first dense, becoming a little looser in age, in fruit again dense, the pods crowded into subglobose or cylindric heads (0.5)1—4 cm. long; calyx 5—7.3 mm., the tube 3.2—4.5 mm. long, 2.1—2.5 mm. in diameter, the subulate teeth 1.5—2.8 mm. long; petals whitish, or veined with purple on a whitish or yellowish ground, sometimes all but the pallid wing-tips reddish-purple; banner 8.2—11.5 mm. long; wings 7.7—10.6 mm., the blades 5.4—7.3 mm. long; keel 6—8.5 mm., the blades 3—4.4 mm. long; pod plumply ovoid-acuminate, bladdery-inflated, 0.9—1.7 cm. long, 8—14 mm. in diameter, broadly rounded or subumbilicate at base, the declined, triangular- acuminate beak 3—5 mm. long, the pale green but purple-mottled, strigulose valves becoming papery-membranous, subdiaphanous, stramineous and lustrous, the septum complete, 3—4.6 (5) mm. wide, the funicular flange 0.4—1.2 wide, ovules 10-15—Collections: 16 (iii); representative: Elmer 3627 (CAS, NY, POM); Ripley & Barneby 5853 (CAS, NY, RSA); Purpus 5760 (POM, UC); Alexander & Kellogg 3009 (NY, WS).

Alkaline, summer-dry flats on the desert floor and about seepage areas in the lower foothills, in stiff clay soils moist in spring, 2100-4700 feet, locally plentiful along the east base of the southern Sierra Nevada, California, but the known stations few and widely separated: Big Pine and Lone Pine, Inyo County, Muroc, Kern County; and extending over a rather extensive area around Lancaster, Los Angeles County.—Map No. 128.—April to July.

Astragalus lentiginosus var. albifolius (white-leaved) Jones, Rev. Astrag. 124, Pl. 23. 1923.—‘Tone Pine Owen’s Valley California ... ’’—Holotypus, collected May 14, 1897, by M. E. Jones, POM! isotypi GH, NY!—Cystium albifolium (Jones) Rydb. in N. Amer. Fl. 24: 413. 1929. A. albifolius (Jones) Abrams, I11. Fl. Pac. St. 2: 598, fig. 2874. 1944 (non Freyn & Sint., 1893).

The var. albifolius and the next in order, var. sesquimetralis, have become adapted to a specialized environment of alkaline flats and seepages, where the soil is waterlogged in spring and dries out slowly but never to any great depth during the heat of summer. The presence of water within permanent reach of the deeply penetrating taproot, even though this water may be almost saturated with mineral salts, enables the plants to maintain active growth for a month or more after the sympatric forms of A. lentiginosus, which are native to porous soils on the open desert floor, have perished or fallen into a dormant state; consequently the stems elongate almost indefinitely, sometimes becoming a yard in length. At first or permanently prostrate, trailing over the bare clay or through a thin carpet of saltgrass, the divaricately branching stems sometimes clamber up through low bushes of A triplex or other suffruticulose halophytes and are difficult to extricate unbroken. The var. albifolius, which has essentially the flower of all nine varieties described up to this point, resembles some forms of var. floribundus in its short leaves, crowded leaflets, and densely many-flowered racemes, although these features are combined here with silvery (not green) herbage, the leaflets being ordinarily more densely pubescent above than beneath. The declined (that is forwardly and downwardly directed) beak of the pod is found in var. albifolius alone of all forms of the freckled milk-vetch and provides an easily observed differential character.