Astragalus chamaemeniscus 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
"Nevada: ... in the valley of the White River near Sunnyside, Nye Co., alt. 4900 ft., 25 May, 1941, fl. & fr., Ripley & Barneby No. 3164. —Holotypus, CAS! isotypi, K, RSA!
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Description
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Species Description - Low but relatively slender, densely or sometimes thinly villous-hirsutulous with fine, spreading and incumbent hairs up to 0.7-1.1 mm. long, the herbage canescent or greenish-cinereous, the leaflets bicolored, glabrous above; stems several, decumbent and radiating, 3-13 cm. long, simple or sparingly branched at base, the 2-4 lowest nodes subterranean, pallid, nearly glabrous; stipules membranous, 3-7 mm. long, the lower ones ovate, obtuse, semi- or almost fully amplexicaul-decurrent, the upper ones progressively narrower, the uppermost lanceolate, acute; leaves 2-8 cm. long, all petioled, with (9) 15-19 (21) obovate, oblong-obovate, rarely oblanceolate, obtuse or emarginate, flat or loosely folded leaflets 3-11 mm. long; peduncles 1.5-5 cm. long, incurved-ascending at anthesis, reclinate in fruit; racemes loosely but shortly (3) 5-10-flowered, the flowers ascending, the axis little elongating, 0.5-2 cm. long in fruit; bracts membranous, ovate- or lance-acuminate, 2.5-4.5 mm. long; pedicels at anthesis ± 1.5 mm. long, in fruit thickened, 1.5-3 mm. long; bracteoles 2, minute; calyx 5.8-8 (10) mm. long, the disc 0.7-1 mm. deep, the deeply campanulate or cylindric tube 4.7-7 mm. long, 2.8-3.2 (3.5) mm. in diameter, the subulate teeth 1.1-2 (3) mm. long, the ventral pair shortest and broadest; petals reddish-violet or clear rosy-pink, with a pale, striate lozenge in the banner, the color fugacious; banner recurved through ±: 40°, rhombic-ovate, 13.5-16 (19) mm. long, 6.8 7.5 (9) mm. wide; wings 13-15 (17) mm. long, the claws ± 6 (6.5) mm., the oblanceolate, obtuse or obscurely emarginate, nearly straight blades 7.6-8.5 (9.5) mm. long, 1.9-2.2 (3) mm. wide; keel 10.2-11.5 (15) mm. long, the claws ± 6 mm., the half-obovate blades 5.2-5.6 (7.3) mm. long, 2.5-2.7 (3.2) mm. wide, incurved through ± 65° to the rounded apex; anthers 0.65—0.75 mm. long; pod loosely spreading, ascending, or declined (humistrate), narrowly crescentic in profile, incurved through 1/6-1/3-circle, (2) 2.5-4.5 cm. long, 5-8 mm. in diameter, cuneately contracted at base into a stout, necklike stipe 1—2.5 mm. long (this concealed by the marcescent calyx), abruptly acute or acuminate and cuspidate at apex, triquetrously compressed, with acute ventral and obtuse lateral angles, widely and openly sulcate dorsally, the green, scarcely fleshy valves becoming stramineous, leathery, prominently cross-reticulate, thinly villosulous, inflexed as a complete septum 3.5—4.2 mm. wide; seeds pale brown, pitted, ± 3 mm. long.
Distribution and Ecology - Low knolls, gently sloping gullied hillsides, and valley floors, in deep, sometimes alkaline sands derived from limestone, often scattered among and taking shelter under sagebrush, 4900—6500 feet, local but forming colonies, known only from eastcentral Nevada, in northeastern Lincoln, White Pine, and adjoining Nye Counties.—Map No. 62.—Mid-April to early July.
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Discussion
The ground-crescent milk-vetch is a low and inconspicuous astragalus, but at close quarters a delightful one, with pronounced individuality. It flowers at the onset of spring weather, and the rapidly developing fruits reach their full size, although not full maturity within a few weeks. The rather slender peduncles are quickly crescent-shaped pods which lie in a ring on the ground, often largely concealed by leaves, and tend to fall at random angles to the raceme-axis. It is therefore difficult to say whether the fruits are by nature ascending or declined. The pod of A. chamaemeniscus is quite similar to that of A. malacus in shape and size, but it is more prominently reticulate when ripe, villosulous with much shorter hairs, and never mottled. The flowers are commonly of moderate size, the high measurements for the petals given in parentheses above being taken from a single plant which was growing with the ordinary form in western White Pine County. The petals vary from reddish-violet, the color of A. malacus, to a clear rosy-pink, but the pigment fades rapidly in pressed specimens.
The ground-crescent milk-vetch was collected first by Marcus Jones in the spring of 1893 in the east foothills of the Schell Creek Range near Aurum. His specimens were in flower only and were distributed (NY) as A. cibarius.
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Objects
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Distribution
Nevada United States of America North America|