Astragalus miser var. oblongifolius (Rydb.) Cronquist
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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
"Colorado: Cerro Summit, 1901, Baker 409 ... Holotypus, collected by C. F. Baker, July 12, 1901, NY! isotypi, US, WS!
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Synonyms
Homalobus oblongifolius Rydb., Astragalus hylophilus var. oblongifolius (Rydb.) J.F.Macbr., Astragalus decumbens var. oblongifolius (Rydb.) Cronquist, Homalobus decurrens Rydb., Astragalus rydbergii J.F.Macbr., Astragalus decumbens var. decurrens (Rydb.) Cronquist, Astragalus miser var. decurrens (Rydb.) Cronquist, Homalobus humilis Rydb., Astragalus carltonii J.F.Macbr., Homalobus microcarpus Rydb., Homalobus hitchcockii Rydb.
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Description
Variety Description - Variable in stature, the stems (1) 2-20 (24) cm. long; herbage quite thinly to rather densely strigulose-pilosulous with mostly straight hairs up to 0.35-0.65 (0.75) mm. long, the leaflets green (in some colonies cinereous), the leaflets nearly always glabrous or medially glabrescent above; leaves (2) 4-20 cm. long, with (9) 11-19 (21) linear, Unear-oblong, -elliptic, to broadly oblong or oval- elliptic, mostly acute, rarely obtuse or emarginate, flat or folded (if both folded and narrow, then subfiliform and often falcately curved) leaflets (3) 5-30 (42) mm. long, the terminal one either longer than and remote from the uppermost pair, less often contiguous to it and then either much or scarcely longer, in either case either jointed or continuous with the rachis; racemes 3-15 (25)-flowered, the axis (1) 1.5-10 cm. long in fruit; calyx (2.8) 3.4-5.2 mm. long, the tube 2.2-2.9 mm., the teeth (0.8) 1-25 mm. long; petals whitish, sometimes suffused with dull lilac or lilac-veined; banner (5.9) 6.5-9.5 (10.2) mm. long, (4.6) 5-7.8 mm. wide; wings 5.5-7.6 (8.2) mm. long, the claws 1.5-2.3 (3.2) mm., the blades 4-6.3 mm. long, 1.5-3.3 mm. wide; keel 6.1-8.4 mm. long, the claws 1.6-2.7 mm., the blades (4.2) 4.5-6.7 mm. long, (1.7) 2-2.6 (3) mm. wide; pod (1.2) 1.5-2.5 cm. long, oblanceolate in profile, (1.9) 2.3—4 mm. wide in the upper third, tapering downward into the calyx, the valves strigulose, sometimes dotted or suffused with purple but not mottled; ovules (13) 14-19.
Distribution and Ecology - Dry hillsides among sagebrush, about oak thickets, ascending in open places through the timber belt where found also in shade of aspens and in humus under pines and firs, (5500) 6000-10,300, rarely 11,300 feet, in the Rocky Mountains on granitic formations but on sedimentaries westward, frequent and locally abundant on both slopes of the Divide in Colorado, from the Sangre de Cristo Mountains and Gunnison Valley north to the upper Platte and Laramie Plains in southern Wyoming, west through the Uinta Mountains and on scattered peaks within the Colorado Basin to the plateaus of central and southwestern Utah, northwestern and central Arizona, and to the Schell Creek and White Pine Mountains in eastcentral Nevada.—Map No. 19.—Late May to August.
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Discussion
The var. oblongifolius as circumscribed above is the only representative of the weedy milk- vetch known to occur in the mountains of Colorado, southeastern Wyoming, Arizona, and most of Utah, although its range slightly overlaps that of var. tenuifolius in the northwestern part of the latter state and possibly also in eastern Nevada. In the areas of overlap it is distinguished by its more numerous leaflets and oblanceolate rather than truly linear pod. Variation in stature, in size and shape of the leaflets, and in length of the fruits is implicit in the foregoing description of var. oblongifolius and has been analyzed in a revision of the species (Barneby 1956, p. 480), to which the reader should turn for details concerning most of Ryd- berg’s segregates, here mentioned only in the synonymy. Several minor variants can often be selected out of a given population and only one of them, the so-called var. decurrens, is dominant in a significantly definite segment of the variety’s range. My concept of var. oblongifolius is embodied in the collections already cited and includes var. decurrens. The latter is found along the east slope of Colorado’s Front Range from the Cache-la-Poudre River southward to South Park and is ideally distinguished by its long, distantly disposed leaflets (up to 4 cm. long), the terminal one commonly remote from the last pair and usually continuous with the rachis (cf. Clokey 3201, CAS, NY). However, individual plants of this type, and many more of a transitional nature, are known to occur within heterogeneous populations of A. miser on both slopes of the Front Range and (more rarely) elsewhere in Colorado. It may be worth noting in this connection that duplicate sheets of one collection (Jones 528, from Golden, NY) were identified by Rydberg as Homalobus decurrens and H. microcarpus, respectively.
The two collections from Arizona referred to var. oblongifolius are scanty but unquestionably of this species. That from farthest south (junction of Young-Payson road, Gila County, Goodding, cited above) is very condensed, but a good match for some material from high elevations on the Wasatch Plateau in Utah. The other, from the Kaibab Plateau (V. T. Ranch, Jacob Lake Highway, Coconino County, Goodding 244—48, ARIZ) would run in the varietal key to var. tenuifolius, for the leaflets are reduced to three pairs at most. The plants are further unusual for the length and slenderness of the caudex branches, evidently partly subterranean, as though buried in mobile gravel or possibly forest litter. The pubescent ovary and ovule-number (14) are consonant with var. oblongifolius and the collection has been mapped as such.
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Objects
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Distribution
Colorado United States of America North America| Wyoming United States of America North America| Utah United States of America North America| Arizona United States of America North America| Nevada United States of America North America|