Astragalus lentiginosus var. fremontii (A.Gray ex Torr.) S.Watson
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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
Astragalus lentiginosus var. fremontii (A.Gray ex Torr.) S.Watson
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Type
"Banks of the Rio Virgin, May 3, 1844, Fremont."—Holotypus, NY (herb. Torr.)! isotypus, GH!
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Synonyms
Astragalus fremontii A.Gray ex Torr., Astragalus coulteri var. fremontii (A.Gray ex Torr.) M.E.Jones, Cystium fremontii (A.Gray ex Torr.) Rydb., Astragalus eremicus E.Sheld., Cystium eremicum (E.Sheld.) Rydb., Astragalus fremontii subsp. eremicus (E.Sheld.) Abrams, Cystium griseolum Rydb.
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Description
Variety Description - Annual, biennial, or perennial of short duration, with a solitary and erect or more often several diffuse and ascending stems, densely to quite thinly strigulose or more rarely villosulous with straight and appressed or narrowly ascending, with all incumbent, or with all or mostly sinuous or curly hairs up to 0.3-0.75 mm. long, the herbage mostly cinereous or canescent, sometimes green, more rarely silvery-silky, the leaflets nearly always pubescent on both sides, occasionally glabrous above, or more densely pubescent above than beneath; stems stout or slender, (0.4) 0.8-3.5 (4) dm. long; leaves (3) 4-9 (12) cm. long, with (9) 11-19 ovate- or obovate-cuneate, broadly oblanceolate, or rhombic-elliptic, obtuse, emarginate, or rarely subacute, flat or loosely folded leaflets 5—19 mm. long; peduncles erect or incurved, 2.5-8.5 (10) cm. long, a little longer or shorter than the leaf; racemes loosely (8) 10-30-flowered, the axis (2.5) 4—11 (16) cm. long in fruit; calyx (3.4) 3.8-6 (7.9) mm. long, strigulose or villosulous with black, white, or mixed hairs, the tube (2.8) 3—4.5 mm. long, 1.9-2.6 mm. in diameter, the teeth (0.6) 0.9-2 (3.5) mm. long; petals bright purple, occasionally varying through shades of pink-lilac to pure white in the same colony; banner 9.1-12 (12.4) mm. long, (4.2) 5-7 (7.8) mm. wide; wings (7.4) 8-10.6 mm., the claws (2.7) 3-4.4 mm., the blades 5.2-7.3 mm. long; keel (5.6) 6.2-8.6 mm. long, the claws (2.8) 3.1-4.6 mm., the blades (3.1) 3.4—4.8 mm. long, (1.8) 2-2.5 mm. wide; pod nearly always bladdery-inflated, broadly and plumply or rarely quite narrowly ovoid-acuminate, 1.4-2.7 (3.6) cm. long, (5) 8-18 mm. in diameter, contracted or more rarely tapering into a more or less incurved, unilocular beak (2) 3-7 (10) mm. long, the pale green, often purple-freckled or -mottled, glabrous or thinly strigulose-villosulous valves becoming papery-membranous, lustrous, subdiaphanous, the septum complete or nearly so; ovules (17) 19-31.
Distribution and Ecology - Sandy flats, washes, desert playas, gravelly hillsides, and open valleys, with creosote-bush, Joshua-tree, greasewood, sagebrush, rabbit-brush, and in piñon- juniper forest, most common and abundant in loose sandy soils but with no apparent rock preference, mostly from 3000 to 6500 feet, but ascending in the White and Inyo Mountains to 8200 feet and on the east face of the Sierra Nevada rarely up to the 9000-9500 feet contours (there entering the Jeffrey pine belt), widespread and locally dominant over extensive areas of sandy desert, nearly throughout the south third of Nevada (northeastern Nye County to the Muddy River Valley, west to the White Mountains and south to the Colorado River), west to the head of Owens Valley in Inyo and extreme southern Mono Counties, California, and south to the Argus Mountains and Coso Junction (northeastern Kern County) and through Death Valley to the Clark, New York, Providence, and Old Dad Mountains in the eastern Mohave Desert.—Map No. 130.—Late March to July, sometimes again in September or October.
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Discussion
Fremont’s freckled milk-vetch may be distinguished ideally, and is in practice nearly always so, by its small flowers of a lively purple arranged in loose, finally elongating racemes. It is one of the commonest and most abundant astragali over a great part of southern Nevada and the northern and eastern Mohave Desert in California, sometimes found in vast numbers over the floor of desert valleys, whence it extends upward into the foothill canyons. In Lincoln County, Nevada, an albino mutant occurs rather commonly among the normal purples, sometimes associated with intermediate color-forms grading from palest shell-pink into deep claret- or violet-purples. Within its area of dispersal var. Fremontii is the only form of the species known to occur at low elevations, but at the periphery it passes northward into var. Kennedyi and southwestward, at the base of the Sierra Nevada, into var. variabilis. Variation in amount and orientation of the pubescence has been described above. The vesture tends to become increasingly dense as var. Fremontii is traced westward into California, the tendency culminating in the silvery-canescent phase described as A. eremicus, especially common in alkaline sandy soil around Owens Lake. Normally appressed or subappressed, the hairs on the leaves and stems, but especially on the latter, are often both loose and copious in the foothills of the White and Inyo Mountains; and in the same region the stems, particularly between 6000 and 8000 feet, tend to become short and diffuse, while the racemes at the same time fail to elongate in fruit. Plants exhibiting all of these peculiarities at once are quite uncommon, and I feel confident that Cystium griseolum, based on two collections of this sort from western Esmeralda County, Nevada, is best treated as a minor variant. Of theoretical interest because of its resemblance in all details but the purple flower to var. macrolobus, it serves as an additional link between the group of varieties exemplified by the soundly perennial, prostrate vars. lentiginosus, salinus, macrolobus, and ineptus with small, shortly racemose, whitish flowers, and the shorter-lived, often monocarpic or annual group of the southern deserts with their more or less erect stems and racemes of loosely disposed, mostly larger, and purple flowers.
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Objects
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Distribution
Nevada United States of America North America| California United States of America North America|