Astragalus sinuatus Piper
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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
"Eastern Washington, without definite locality, Brandegee, no. 739, in 1883."—Holotypus, Brandegee 729 (!), GH!
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Synonyms
Phaca sinuata (Piper) Piper, Homalobus sinuatus (Piper) Rydb., Astragalus whitedii Piper, Homalobus whitedii (Piper) Rydb.
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Description
Species Description - Robust and leafy, with a woody taproot and knotty or shortly forking, multi- cipital root-crown, villosulous throughout with rather stiff, spreading-incumbent or curly hairs up to 0.4-0.6 mm. long, the herbage densely cinereous, the leaflets somewhat bicolored, equally pubescent on both sides but the upper one brighter green beneath the vesture; stems numerous, decumbent with ascending tips, simple or sometimes branched below, 2-4.5 dm. long; stipules 2-4.5 mm. long, the lowest ones papery, approximate, semiamplexicaul-decurrent, the upper ones herbaceous, ovate-acuminate or deltoid, the blades often reflexed; leaves 2-7 cm. long, widely spreading, all but the lowest sessile or nearly so, with (9) 11-17 (19) obovate- cuneate or oblong-oblanceolate, mostly truncate-retuse or a few very obtuse, flat or loosely folded leaflets (4) 6-16 mm. long; peduncles erect or incurved-ascending, 4.5-12 cm. long, equaling or longer than the leaf; racemes 8-16-flowered, rather dense at early anthesis, loose in age, the flowers ascending, the axis 1.5-4.5 cm. long in fruit; bracts submembranous, triangular-ovate or lanceolate, 2-3 mm. long; pedicels at anthesis ascending, straight, slender, 1.5-2 mm. long, in fruit a little thickened, gently arched outward, 2.7-3.5 mm. long; bracteoles almost always 2; calyx 9-11.5 mm. long, rather densely villosulous with black or mixed black and white hairs, the obliquely campanulate or broadly obconic disc 1.4—2 mm. deep, the membranous, pallid, campanulate to subcylindric, somewhat tumid tube 6.9-8.5 mm. long, 3.7-4.7 mm. in diameter, the triangular-subulate teeth 1.4-3 mm. long, the ventral pair broadest but either longer or shorter than the rest, the whole becoming papery, marcescent unruptured; petals whitish, concolorous, or the keel-tip faintly maculate; banner broadly rhombic- or oblanceolate- spatulate, deeply notched, 16.6-20 mm. long, 7.7—10.5 mm. wide; wings 14.5-17.3 mm. long, the claws 7.3—8.9 mm., the oblong or lance-oblong, obtuse blades 7.9-9.5 mm. long, 2.5-3.1 mm. wide, straight or a trifle incurved distally; keel 12-13.4 mm. long, the claws 7.1-8.4 mm., the lunately triangular blades (5) 5.5-6.7 mm. long 3.1-3.5 mm. wide, incurved through 85-90° to the bluntly deltoid apex; anthers 0.6—0.85 mm. long; pod spreading horizontally or pendulous, stipitate, the straight stipe 5—8 mm. long, the falcately oblong body (1.8) 2—3 cm. long, (4) 5—7 mm. in diameter, cuneate at base, cuneately tapering at apex into a subulate cusp ± 2.5 mm. long, laterally compressed, carinate by both sutures, the ventral one cordlike, the dorsal one equally salient but narrower, sinuate in age, the green, fleshy, densely villosulous valves becoming stramineous, stiffly leathery or subligneous, transversely rugulose-reticulate, not inflexed; ovules 24—30; seeds brown, smooth but dull, ± 3.5 mm. long.
Distribution and Ecology - Dry hillsides, probably among sagebrush, ± 2000 (?) feet, known certainly only from Colockum Creek, a small tributary of the Columbia River in Chelan County, Washington.—Map No. 30.—Mid-April to June.
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Discussion
The Whited milk-vetch is one of several species first discovered by Brandegee and Tweedy on the Northwestern Expedition organized by William Canby. The material of this collection, very valuable and novel at the time, was distributed without exact locality data, and nothing seems to be known of the route followed by the expedition’s members. Only one specimen of A. sinuatus seems to have been collected, for the type number is not represented in the Canby herbarium (NY). It is fair to assume that it came from the Columbia Valley in Chelan County or the immediate neighborhood, as the species has been collected subsequently only along Colockum Creek. The type-collection of A. Whitedii, unlike that of A. sinuatus which is in advanced fruit, bears flowers and pods not fully ripened; but there can be no doubt that, as Piper himself early realized (1906, 1. c.), it represents the same species as Brandegee’s plant, for the specimens are closely similar in foliage, vesture, and what can be compared of the calyces at such different stages of growth. Nevertheless the two collections have long been treated as representing different species. Jones (1923, Index) listed A. sinuatus in the synonymy of A. Gibbsii, a species not known to occur within several hundred miles of eastern Washington, and A. Whitedii in that of A. speirocarpus, the ripe fruit of which is altogether different. In a sense, Jones’s treatment contrives a composite portrait of A. sinuatus, for it might be described as resembling A. speirocarpus up to the flower, then putting forth a fruit almost like that of A. Gibbsii. Rydberg (1924, p. 16) maintained A. sinuatus as a distinct species of Homalobus, known to him from the typus only, but misinterpreted A. Whitedii as the earliest valid synonym of what is now known as A. (Collini) curvicarpus. These two species are similar in habit, vesture, and fruit, but differ in the form and orientation of the flower. Moreover, the range of typical A. curvicarpus lies well south of Washington.
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Objects
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Distribution
Washington United States of America North America|