Monographs Details: Astragalus lemmonii A.Gray
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
Discussion:

348.  Astragalus Lemmoni

Delicately slender, diffuse, with a stout, woody taproot and at length knotty root-crown or shortly forking caudex, sparsely strigulose with fine, straight, appressed or some narrowly ascending hairs up to 0.25-0.5 mm. long, the stems sometimes glabrous, the herbage green, the leaflets glabrous or nearly so above; stems several or numerous, prostrately radiating, 1—4 (5) dm. long, simple or sparingly branched at base, thereafter bearing a peduncle or a peduncle and spur together in each axis, floriferous upward nearly its whole length, the spurs upward reduced to a single peduncle (or two) and the racemes then disposed in unequal pairs (or threes); stipules submembranous becoming pallid and scarious, ovate- or triangular-lanceolate, 2-5 mm. long, decurrent around half or nearly the whole stem’s circumference, free; leaves (1) 1.5—4.5 cm. long, all or at least the lowest petioled, the uppermost commonly subsessile, with (7) 9-15 narrowly elliptic or elliptic-oblanceolate, acute or subacute, rarely truncate-emarginate, flat or loosely folded leaflets 2-11 mm. long; peduncles slender, ascending, 6-17 mm. long, much shorter than the leaves; racemes loosely but shortly (2) 5-13-flowered, the flowers loosely ascending, the axis scarcely elongating, 2—10 mm. long in fruit; bracts membranous, ovate or lance-ovate, 0.8-2 mm. long; pedicels subfiliform, at anthesis ascending, 0.7-2 mm. long, in fruit arched outward, 0.9-2.5 mm. long, scarcely thickened, but the fertile ones persistent; bracteoles 0; calyx 3-3.9 mm. long, strigulose with white or sometimes a few black hairs, the symmetric disc 0.3—0.6 mm. deep, the campanulate tube 1.7—2.2 mm. long, 1.4—1.8 mm. in diameter, the subulate teeth 1.1-1.7 mm. long, the whole becoming papery, ruptured, persistent; petals whitish or tinged with lilac, the banner sometimes dull purple-veined; banner recurved through 45—85°, rhombic-obovate or broadly rhombic-oblanceolate, 4.8-6.1 mm. long, 2.8-4.5 mm. wide; wings 4.4—5.9 mm. long, the claws 1.5-1.9 mm., the oblong-elliptic, obtuse, strongly incurved blades 3.1-4.6 mm. long, 1.4—1.9 mm. wide; keel 3.4—4 mm. long, the claws 1.4—1.8 mm., the asymmetrically half-circular blades 2-2.7 mm. long, 1.3—1.5 mm. wide, abruptly incurved through about 135° to the triangular, obtuse, somewhat porrect apex; anthers 0.3—0.4 mm. long; pod spreading or a trifle declined, sessile, elliptic or oblong-elliptic in profile, straight or a trifle incurved, 4—7 mm. long, 1.5—2.5 mm. in diameter, obtuse at base, abruptly triangular-acute at apex, compressed-triquetrous with nearly flat lateral and narrower, sulcate dorsal faces, carinate ventrally by the suture, the lateral angles obtuse, the thin, pale green, strigulose valves becoming papery, stramineous or brownish, faintly cross-reticulate, inflexed as a complete or nearly complete septum 0.8-1.3 mm. wide; ovules 4-8; seeds chestnut-brown, smooth but dull, 1.2—1.6 mm. long.—Collections: 18 (o); representative: Maguire & Holmgren 26,472 (NY, RSA, TEX, WS); Eastwood & Howell 7962 (CAS); Eastwood 7791 (CAS, POM, UC); Lemmon 50, 72 (MO, NY); Peirson 10,744 (RSA).

Forming colonies in moist, but often summer-dry meadows and rushy flats along stream and lake shores, 4200-5200 feet, scattered and not common, along the east foothills of the Cascade Range and Sierra Nevada and plains immediately adjoining, from near the head of the Deschutes River in central Oregon south to Sierra Valley, California, and western Washoe County, Nevada; apparently isolated, at 6700-7000 feet, on upper Owens River, Mono County, California.— Map No. 157.—Late May to August.

Astragalus Lemmoni (John Gill Lemmon, 1832-1908, pioneer botanical collector in the n. Sierra Nevada in the 1870’s) Gray in Proc. Amer. Acad. 8: 627. 1873.—"Sierra Valley, Sierra County, California, J. G. Lemmon, communicated by Dr. Bolander."—Holotypus, collected in June, 1872, GH! The spm. at NY dated May 10, 1872, is perhaps an isotypus.—Tragacantha Lemmoni (Gray) O. Kze., Rev. Gen. 946. 1891.

The Lemmon milk-vetch is a rare little astragalus, remarkable morphologically for its racemes of tiny flowers borne on short peduncles in pairs or fascicles of three at all nodes above the last lateral branch, and physiologically for its adaptation to moist alkaline habitats on the banks of streams or the shores of Basin lakes. It was associated by Jones (1923, p. 276) with some small-flowered members of the largely Mexican sect. Strigulosi. Technical characters of free stipules and deciduous pod suffice to exclude A. Lemmoni from the Strigulosi, although the imponderable differences of growth-habit are equally decisive. Rydberg (1929, p. 453) transferred the species to his sect. Lentiformes in company with A. Lyalli and A. lentiformis. These are characterized by equally small flowers and fruits of similar size and structure, but are quite diverse in other respects. The Lemmon milk-vetch resembles A. Lyalli in its free stipules but differs in its short, few-flowered racemes and pod deciduous from the persistent pedicel and calyx; A. lentiformis, with similar inflorescence, has connate stipules and pedicels disjointing in age. From the Chaetodontes as a whole A. Lemmoni stands apart because of its thin, appressed vesture and mesophytic habitat, but it is probably a highly specialized member of the group.