Astragalus minthorniae var. villosus 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(1): 1-596.
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Family
Fabaceae
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Scientific Name
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Type
"California: Inyo Mountains 12 miles east of Zurich, Inyo Co., alt. 7200 ft., 18 May, 1944, Ripley & Barneby 4951."—Holotypus, CAS! isotypi, GH, NY, RSA!
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Description
Variety Description - Caudex superficial; stature variable, the stems either slender and with only 2 developed internodes, or coarse and robust, up to 3.5 dm. long; herbage and stems villosulous, the lowest, sheathing stipules pilose-canescent; petals either ochroleucous with maculate keel-tip, or pink-purple with pale or white wing-tips; pod almost as in var. Minthorniae, but often more densely shaggy-villous with white or partly black hairs 0.6—1.3 mm. long.
Distribution and Ecology - Rocky hillsides, gravelly benches, and canyon washes, sometimes among sagebrush on valley floors, usually in juniper-piñon forest, strongly and perhaps obligately calciphile, 4400—7800 feet, common and locally plentiful in the foothills of the Spring and Charleston Mountains of southern Clark County, Nevada, and of the New York, Clark and Kingston Ranges of adjoining San Bernardino County, California, extending north, apparently disjunctly, to the Inyo Mountains, Inyo County, and to Gold Mountain across the Nevada fine; also quite isolated on the calcareous enclave of Cushenbury Canyon in the San Bernardino Mountains, southwestern San Bernardino County.—Map No. 60.—Late March to June.
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Discussion
The villous variety of the Minthorn milk-vetch varies greatly in stature, probably in response to seasonal fluctuation in rainfall. The stems of the dwarf state consist of several inhibited lower internodes concealed by densely hairy stipules and sometimes no more than two developed ones; in such individuals the peduncles appear subscapose and the plant’s whole habit of growth is comparable to that of the Conjuncti and several Reventi-Arrecti. More often, however, several internodes are produced and the peduncles become obviously lateral and cauline. The shaggy vesture of the erect, oblong-cylindric pod is ordinarily composed of long, silvery hairs mixed with shorter, black ones, but the latter are sometimes few or lacking.
The var. villosus was first collected in 1882, by the Parish brothers, in its isolated station in Cushenbury Canyon, and again before the turn of the century by Purpus in Nevada. Jones must have seen both these collections, as well as several later ones, misinterpreting them as a form of A. malacus or as an imaginary hybrid between A. malacus and A. Layneae. A specimen of var. villosus collected by the Brandegees at Good Springs, Nevada (UC) is labeled by Jones "A. Layneae intergradient to A. malacus," although this is not the original A. malacus X Layneae which came from Inyo County (cf. discussion of A. Layneae). The Minthorn milk-vetch in all its forms is easily distinguished from A. Layneae by its determinate (never stoloniferous), commonly superficial root-crown and by its erect, persistent, shorter, laterally and not dorsiventrally compressed legume.
The established range of var. villosus lies well to the west and south of that of var. Minthorniae, but the gap between them as shown on the map is possibly less real than apparent. The territory lying between the Charleston massif and the headwaters of the Muddy River in southern Nevada has always been difficult of access and is still poorly known botanically.
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Objects
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Distribution
Nevada United States of America North America| California United States of America North America|