Astragalus scaphoides (M.E.Jones) Rydb.
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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 sagebrush areas, 5500° alt., Beaver Head County, Montana, on hills west of Clark’s Cañon, July, 1888."—Holotypus, collected by Frank Tweedy, No. 9 in 1888, US! isotypi, NY, POM (fragm.)!
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Synonyms
Astragalus arrectus var. scaphoides M.E.Jones, Phacopsis scaphoides (M.E.Jones) Rydb., Hesperonix scaphoides (M.E.Jones) Rydb.
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Description
Species Description - Relatively stout, with a woody taproot and knotty, shortly forking caudex, strigulose with fine, mostly straight, appressed hairs, the herbage subcinereous when young, the leaflets bicolored, gray-green beneath, brighter green and glabrous above; stems several or numerous, erect and ascending in clumps, (1) 1.5-4 dm. long, simple or spurred below the middle, commonly purple-tinged, composed of about 4-8 developed internodes, that preceding the first peduncle usually the longest; stipules submembranous, early becoming papery, 3-8 mm. long, the lowest ovate, obtuse, semiamplexicaul-decurrent, the median and upper ones narrower, ovate-acuminate, deltoid, or broadly lanceolate, obtuse or acute; leaves (6) 8-20 (24) cm. long, all petioled but the upper ones shortly so, with (9) 17-25 oblong, elliptic, rhombic-ovate, or -lanceolate, or (in some upper leaves) linear-elliptic, obtuse or subacute, flat leaflets (7) 10-20 (28) mm. long; peduncles stout, stiffly erect, 8-16 cm. long; racemes (9) 15-30-flowered, the flowers widely spreading or loosely nodding, rather crowded at early anthesis, the axis soon elongating, (3) 5-17 cm. long in fruit; bracts membranous, lanceolate, 2-4.5 mm. long; pedicels at anthesis 1.5-2.5 mm. long, in fruit clavately thickened, straight or nearly so, ascending, 2.5-5 mm. long; bracteoles usually 2, attached at base of calyx or on the pedicel; calyx 9.6-12.2 mm. long, loosely strigose-pilosulous with black or black and white hairs, the strongly oblique disc 1.2 1.5 mm. deep, the subtumid, pallid, deeply campanulate tube 7-9 mm. long, 4.2-5 mm. in diameter, the lance-subulate teeth (1) 2-3.2 mm. long; petals ochroleucous, immaculate; banner recurved through ± 50°, rhombic-obovate or -oblanceolate, shallowly notched, 18.5—20.5 mm. long, 8—10 mm. wide; wings 16—17.4 nun. long, the claws 7.4—8.7 mm., the oblong-oblanceolate, obtuse, nearly straight or lunately incurved blades 8.4-10.1 mm. long, 2.8-3.3 mm. broad, keel 13—15 mm. long, the claws 7.5—9.1 mm., the half-obovate blades 5.5-7.3 mm. long, 3-3.2 mm. wide, abruptly incurved through 90° to the bluntly deltoid apex; anthers 0.55—0.75 mm. long; pod long-stipitate, the slender but rigid stipe 12-18 mm. long, ascending and incurved to bring the body to vertical, the subsymmetrically oblong- or ovoid-ellipsoid body moderately inflated, (1.1) 1.4—2.2 cm. long, (4.5) 6.5—10 mm. in diameter, straight or nearly so, truncate at base, abruptly contracted distally into a short, triangular, compressed, cuspidate beak, otherwise obcompressed, with openly and shallowly sulcate ventral and dorsal faces and broadly rounded lateral angles, the thinly fleshy, glabrous, green but commonly purple-suffused or -speckled valves becoming leathery, stramineous, reticulate, inflexed as a nearly complete or incomplete septum 1.4— 1.8 mm. wide; ovules 21—32; seeds (not seen ripe) about 3 mm. long.
Distribution and Ecology - Open valleys, low hills, canyon benches, commonly among sagebrush, on either limestone or basalt, 3500-6000 feet, locally plentiful but of restricted range, known only from the foothills of the Bitterroot Mountains and immediately adjoining valleys of the upper Salmon and Lemhi Rivers in eastcentral Idaho and that of Red Rock Creek in western Beaverhead County, Montana.—Map No. 64. —June to early August.
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Discussion
The Bitterroot milk-vetch, A. scaphoides, is a handsome plant, notable for its large, decidedly inflated but by no means bladdery, dorsiventrally compressed pods which are held erect at a distance from the raceme-axis on long, slender but rigid, incurved-ascending stipes. The epithet scaphoides, suggesting a pod keeled on one face and excavated like a boat on the opposite, is quite misleading, for it is precisely the doubly grooved fruit assuming the form of two parallel cylindric chambers partially fused together, separated (more or less completely) in the plane of fusion by the septum, and giving a didymous figure in cross-section, which provides the best differential character of the species as compared with the closely related A. eremiticus. First described by Jones as a variety of A. arrectus, it was maintained bv him (1923, p. 163 Pl. 38) in the same category; but the forms from Weiser (Jones, l.c.) supposedly connecting A. scaphoides with the ‘type" of A. arrectus are simply (cf. Jones from Weiser Idaho, in 1899, in 1900, POM, NY) a minor variant of A. eremiticus, and irrelevant to the case. Doubtless on account of the considerably tumid fruit, Rydberg transferred the species first to Phacopsis and subsequently to Hesperonix where it came to rest (Rydberg, 1929 p. 439) next to A. vallaris, a species coincidentally similar in pod-outline but greatly different in growth-habit and technical detail. According to Rydberg's generic key (1929, p. 252), A. scaphoides might be traced down either to Jonesiella or to Hesperonix depending on the width of the pod's septum in a given plant, a fair example of the quality of these segregate genera.
In Lemhi County, Idaho, the Bittenoot milk-vetch is known to range along the valleys of the Pahsimeroi and Salmon Rivers from Lemhi Pass near Tendoy downstream to Shoup, a distance of some fifty miles. The type-locality has not been located. There is only one exact record from east of the Bitterroots, on lower Red Rock Creek twelve miles above Dillon, at a point about forty miles east of Lemhi Pass. The dispersal of A. scaphoides in Beaverhead County is obviously too little known.
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Objects
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Distribution
Idaho United States of America North America| Montana United States of America North America|