Astragalus bisulcatus var. nevadensis (M.E.Jones) 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
"Collected June 14, 1882, at Palisade, Nevada... distributed as "Astragalus n. sp." in my sets of 1882."—Holotypus, collected by M. E. Jones, POM! isotypi CAS, NY, RM, US!
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Synonyms
Astragalus haydenianus var. nevadensis M.E.Jones
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Description
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Variety Description - Rather slender, the decumbent and incurved-ascending stems 1.5-3 dm. long; herbage green or cinereous; leaflets (7) 11—19, those of the lower leaves sometimes emarginate; racemes (15) 25-45-flowered, narrowly cylindric, the fruiting axis (3) 6-20 cm. long; bracts 1-2.5 mm. long, calyx-tube 2.8-3.2 mm. long, 2—2.3 mm. in diameter, the subulate teeth 0.7—1.6 mm. long; petals dull straw- yellow, the keel tipped with sordid lilac; banner at full anthesis abruptly recurved through ± 130°, 6.7-9.2 mm. long, 3.8-4.8 mm. wide; wings slightly longer, the claws 2.7-3.2 mm., the subsymmetrically elliptic and acute or subacute blades 5.9-7.8 mm. long, 1.9-2.8 mm. wide; keel 8-10.3 mm. long, 0.8-2 mm. longer than the banner, the claws 2.7—3.5 mm., the oblong, subtruncate blades 5.6—7.3 mm. long, 2.5-3.2 mm. wide; anthers 0.45-0.6 mm., long; stipe of the pod 3-3.7 mm. long, the body narrowly ellipsoid, 8—12 mm. long, 2.5—4 mm. in diameter, often strongly decurved, the valves strigulose, delicately reticulate but not rugulose; ovules 6-8.
Distribution and Ecology - Barren knolls, gullied hillsides, and desert sinks, in stiff white or red clays derived from limestone, with piñon, juniper, or sagebrush, 5000—7400 feet, locally abundant in scattered stations in the valleys and foothills of eastcentral Nevada (northwestern Nye, White Pine, Eureka, and probably southern Elko Counties).— Map No. 45.—May to July.
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Discussion
The Nevada two-grooved milk-vetch, resembling var. Haydenianus in general habit of growth and in the small size of the flower and pod, is easily distinguished by the characteristically modified flower, few leaflets, and nearly smooth surface of the ripe pod. The sordid yellow petals and short bracts, though not of great importance as differential characters, add to the individuality of the variety, which occupies a small but compact area of dispersal disjunct from the rest of its species. Despite its likeness to var. Haydenianus, the var. nevadensis is probably derived independently from the so-called Basin Variants of var. bisulcatus, in particular the phase prevalent in southwestern Utah (A. Haydenianus var. major). The pods of these two forms are nearly identical in shape and reticulation, and relatively few (11-19) leaflets are a feature common to both. Broad, thin leaflets stressed as diagnostic of D. Jepsoni by Rydberg (1929, p. 281) are now known to be of rare and sporadic occurrence in the variety.
The var. nevadensis was first collected in 1865 by Dr. Torrey (NY, a "grallator" form), in "the East Range of the Humboldt Mountains," a station probably in Elko County, but too vaguely recorded to permit accurate mapping. The specimen may have been taken on bottomlands of Diamond Valley in northcentral Eureka County, where the Emigrant Trail from Fort Ruby to Austin passes close to stations where var. nevadensis is still abundant.
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Objects
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Distribution
Nevada United States of America North America|