Astragalus sclerocarpus A.Gray
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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
"Dry sandy and barren grounds, at the Great Falls of the Columbia, rare.. .in Mr. Douglas’ collection."—Holotypus collected in 1825, K! isotypi, GH, OXF!
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Synonyms
Phaca podocarpa Hook., Tragacantha sclerocarpa (A.Gray) Kuntze, Homalobus podocarpus (Hook.) Rydb.
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Description
Species Description - Diffuse, wiry, sparsely leafy or somewhat junceous, with a long, woody taproot and shortly forking, sometimes shallowly buried caudex, strigulose nearly throughout with straight, appressed, somewhat flattened hairs up to 0.35-0.5 mm. long, the herbage canescent or in age greenish, the leaflets brighter green and more thinly pubescent, medially glabrescent, or sometimes glabrous above; stems decumbent and distally ascending, or straggling, 2-5 dm. long, leafless at base, usually branched or spurred at 1-3 of the lowest leaf-bearing nodes, thereafter simple, flexuous or zigzag, the main axis composed of ± 10-16 developed internodes; stipules 1.5-5 mm. long, the lowest ovate or broader than long, early becoming papery and irregularly deciduous, amplexicaul-decurrent around 1/2-4/5 the stem’s circumference, the median and upper ones narrower, subherbaceous, with triangular or deltoid, erect or deflexed blades; leaves (3) 5-13 cm. long, shortly petioled or the uppermost subsessile, with (5) 7-17 distant, linear, linear-oblanceolate, or rarely narrowly oblong, in the uppermost leaves often filiform, obtuse or retuse, flat or involute leaflets 3-23 mm. long; peduncles 4-9.5 cm. long, nearly always surpassed by the leaf; racemes loosely (3) 7-21-flowered, the axis elongating, (1) 2.5-6.5 cm. long in fruit; bracts membranous, ovate, acute or acuminate, 1-2 mm. long; pedicels at anthesis ascending, straight, slender, 1-2.5 mm. long, in fruit thickened, arcuately spreading, 1.7-2.5 mm. long; bracteoles nearly always 2; calyx 5.9-8 mm. long, finely strigulose with black or largely black hairs, the slightly oblique disc 1-1.4 mm. deep, the membranous, deeply campanulate or subcylindric tube 5.3-7 mm. long, 2.6-3.6 mm. in diameter, the broadly subulate teeth 0.5-1.3 mm. long, the ventral pair commonly shortest and broadest, the orifice oblique, the whole becoming scarious, marcescent unruptured; petals whitish, the tips of the banner and wings tinged with pale lilac, the keel maculate with dull purple; banner rhombic-obovate, 13-16.3 mm. long, (6.8) 7.5-10 mm. wide; wings 12.8-14.5 mm. long, the claws 5.4-7.8 mm., the oblong or oblong- oblanceolate, obtuse or erose-emarginate, straight or nearly straight blades 7.2 8.2 mm. long, 2.1-2.8 mm. wide; keel 10-12.1 mm. long, the claws 5.3-7.6 mm., the lunately half-elliptic blades 4.6-5.4 mm. long, 2.6-3 mm. wide, incurved through 85-100° to the rounded apex; anthers 0.6-0.8 mm long; pod pendulous, stipitate, the stipe 1.2-2 cm. long, arched downward out of the calyx, sigmoidally incurved distally, very gradually expanded into the body, the latter lunately or falcately ellipsoid, 2-3.5 cm. long, (5.5) 6.5-9 mm. in diameter, long-acuminate at both ends or at base only, then contracted at apex into a stoutly cuspidate beak, subterete when first formed, becoming laterally compressed when ripe or dried, prominently carinate by the thick, salient, cordlike ventral suture and the sometimes undulate dorsal suture, the lateral faces convex, the thick, fleshy, green valves becoming stiffly leathery or subligneous, brownish-stramineous, coarsely rugulose- reticulate, densely or at length thinly strigulose, not inflexed; ovules 30-36; seeds brown, smooth but dull, 1.9—3 mm. long.
Distribution and Ecology - Dunes and sandy barrens, 200—1600 feet, locally plentiful along the banks of the Columbia and more sparingly along the lower Snake and Yakima Rivers from The Dalles upstream to Kettle Falls, in northern transmontane Oregon and eastern Washington, and along the upper Okanogan River in southern British Columbia.—Map No. 30—April to July.
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Discussion
The Dalles milk-vetch, A. sclerocarpus, is an untidily straggling, sparsely leafy herb of pronounced xerophytic habit, remarkable for the large, fleshy, ultimately two-keeled pods exserted from the calyx on long, sigmoidally arched stipes. It is one of the several interesting endemic species encountered along the banks of the Columbia, where it is often associated with A. succumbens. The plants flower in early spring, but are active vegetatively for four or five months, and the pods ripen slowly, seldom reaching the stage of dehiscence before midsummer. When in young flower A. sclerocarpus closely resembles and has been mistaken for its near relative A. speirocarpus, for the leaflets of some early leaves are sometimes comparatively broad and the flowers are almost identical in shape and coloring. The vesture of appressed, somewhat flattened hairs is ordinarily a good differential character in doubtful cases. The leaflets of the upper leaves, developed as the fruits mature, are always much narrower in A. sclerocarpus than in its kindred, often filiform or nearly so, and commonly also reduced in length. The pod varies greatly in outline as viewed in profile, and in curvature from a shallow crescent to an open hook. The body tapers so gently into the stipe that it is difficult to differentiate between the two; distally it varies from long-acuminate to abruptly contracted, terminating in either case in a stout, rigid cusp.
Jones has reported the Dalles milk-vetch from the Malheur River in Oregon, but no confirming specimens have been seen. Possibly he mistook an old flowering collection of A. toanus for A. sclerocarpus, but this is a speculation. A specimen purportedly from "Elko County, Nevada" (C. L. Hitchcock 19,012, WS) is almost certainly mislabeled by accident.
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Objects
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Distribution
Oregon United States of America North America| Washington United States of America North America| British Columbia Canada North America|