Astragalus monoensis Barneby
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Authors
Rupert C. Barneby
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Authority
Barneby, Rupert C. 1964. Atlas of North American Astragalus. Mem. New York Bot. Gard. 13(2): 597-1188.
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Family
Fabaceae
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Scientific Name
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Type
"California: ... near Crestview, Mono Co., 10 Aug. 1938, J. T. Howell No. 14500."—Holotypus, CAS! isotypi, GH, NY, RSA, US!
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Description
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Species Description - Slender, diffuse, with a taproot and subterranean root-crown or (in old plants) shortly forking, suffruticulose caudex, densely silky-villosulous nearly throughout with fine, ascending or some spreading, straight or sinuous hairs up to 0.7-0.9 (1) mm. long, the herbage silvery or sometimes greenish, the leaflets pubescent above and beneath; stems several or numerous, prostrate or decumbent with ascending tips, 0.7-2 dm. long, forming loosely woven mats or sometimes entangled in and weakly scrambling through low sagebrush, simple or more commonly shortly branched or spurred at 1-3 nodes preceding the first peduncle, very slender and buried for a space of 2—6 cm. at base, becoming a little stouter upward; stipules 1-3 mm. long, somewhat dimorphic, those at the buried nodes scarious, pallid, connate into a campanulate, subtruncate or bidentate sheath, the median and upper ones longer, herbaceous or distally so, becoming less strongly connate upward, the uppermost united only at very base, with ovate or deltoid, mostly reflexed blades; leaves (0.7) 1-3 cm. long, shortly petioled or the upper ones subsessile, with 9-13 (15) usually crowded, oval, obovate-cuneate, or oblong-obovate, obtuse, loosely folded leaflets 2-8 mm. long; peduncles incurved-ascending, (1) 2-4.5 cm. long, equaling or commonly surpassing the leaf; racemes very shortly or subcapitately 6-12-flowered, the flowers subhorizontal at full anthseis, the axis little elongating, 5-12 mm. long in fruit; bracts herbaceous becoming papery, ovate or lanceolate, 1.5-3 mm. long; pedicels slender, at anthesis 0.8-1.2 mm. long, in fruit arched outward, little thickened, 1.5-2 mm. long, tardily disjointing; bracteoles commonly 2, sometimes minute or 0; calyx 4.8-6.6 mm. long, villosulous with white, sometimes mingled with a few black hairs, the subsymmetric disc 0.6-0.9 mm. deep, the submembranous, campanulate, pink-tinged tube 3-4.6 mm. long, 2.8-3.3 mm. in diameter, the broadly subulate teeth 1.2-2.1 mm. long, the whole becoming papery, ruptured, marcescent; petals whitish ± tinged with pinkish-lavender, drying yellowish, feebly persisting about the forming pod; banner recurved through ±50°, elliptic-oblanceolate or ovate-cuneate, 10-13 mm. long, 4.8-6.6 mm. wide; wings 9.4-10.8 mm. long, the claws 3.5-4.4 mm., the elliptic, obtuse, slightly incurved blades 6.2-12 mm. long, 2.2-2.9 mm. wide, the inner margin of the left one infolded; keel 6.7-8 mm. long, the claws 3.5-4.2 mm., the half-circular or -obovate blades 3.2-4.2 mm. long, 2.1-2.7 mm. wide, abruptly incurved through 100-125° to the deltoid apex; anthers 0.5-0.6 mm. long; pod spreading or (when humistrate) ascending, sessile, obliquely ovoid-acuminate or lance-ovoid, incurved through ± ¼-½ circle, 1.5-2 cm. long, 6—9 mm. in diameter, rounded or subtruncate at base, contracted upward into a laterally compressed, triangular-acuminate, cuspidate beak, otherwise somewhat obcompressed, with shallowly and openly sulcate dorsal face, rounded lateral angles, and ventral face depressed but carinate by the prominent suture, the slightly fleshy, shortly villosulous valves becoming papery, stramineous, sometimes purple-tinged, cross-reticulate, inflexed below the unilocular beak as a partial or nearly complete septum 1.2-2.2 mm. wide; dehiscence apical, through the gaping beak, the walls of the septum also tardily separating; ovules 18-28; seeds dark chestnut-brown, sometimes almost black, smooth but scarcely lustrous, 2-2.6 mm. long.
Distribution and Ecology - Open slopes and flats, in pumice sand or gravel, sometimes sheltering under low sagebrush, 7500-7900 feet, very local but forming colonies, east slope of the Sierra Nevada about the headwaters of Owens River (Mammoth; Crestview; Big Sand Flat), Mono County, California.—Map No. 134.—Late June to August.
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Discussion
The Mono milk-vetch is an inconspicuous but rather pretty species of humble stature, found on open sandy flats where the plants form loosely woven mats of silvery-villous foliage up to about 3 dm. in diameter but mostly smaller. They sometimes take shelter under Artemisia arbuscula, where the stems become entangled in the twigs of sagebrush and often a little longer. The species is found in the same region as A. Whitneyi var. Whitneyi, in which the leaves are strigulose with appressed hairs and the pod is pendulous, balloon-shaped, unilocular, and narrowed at base into a stipe continuous with the receptacle; and it has been found nearly associated with A. lentiginosus var. ineptus, which may be distinguished by its free stipules, more numerous (mostly 15-21) leaflets, and looser racemes of comparatively many flowers with a deeper and narrower calyx-tube, these being followed by swollen but fully bilocular pods of very thin texture. The species is closely related only to the next. Its known range extends over an area not exceeding fifteen miles in diameter, but it is not uncommon locally, associated with the beautiful evening-primrose, Oenothera xylocarpa Cov. The Mono milk-vetch was first collected on June 26, 1925, by Frank W. Peirson.
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Objects
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Distribution
California United States of America North America|