Astragalus miser Douglas ex Hook.
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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
"On low hills of the Spokan River, sixty miles from its confluence with the Columbia."—Holotypus, from "Sandy banks of the Spokan River, 1826.", BM! isotypus, OXF! phototypus, NY!
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Description
Species Description - Low and closely tufted, or taller and diffuse, with a tough woody taproot and pluricipital root-crown or ultimately branched suffruticulose caudex, thinly to very densely pubescent with appressed or ascending, mostly straight, rarely sinuous or curly, basifixed or dolabriform hairs up to 0.3-1 (1.25) mm. long, the herbage green, cinereous, or silvery-silky (-villous), the leaflets either glabrous or pubescent above; stems usually numerous, arising from buds on the root-stock at or a little above soil-level, commonly of 2 sorts: sterile spurs with inhibited internodes forming a basal leafy tuft, these sometimes issuing from the lowest, approximate nodes of the current season’s stems rather than directly from the caudex; and fertile stems, either decumbent or ascending, 1-35 cm. long, with at least 1 and commonly several developed internodes; stipules 1.5-9 mm. long, all or at least the lowest papery-membranous, pallid or brownish (the uppermost sometimes with herbaceous blades), amplexicaul and connate into a bidentate, often loose sheath, the lowest ones small, the upper progressively longer and more shortly united, the uppermost often joined by a low collar or stipular line, with lance-acuminate, erect or spreading blades; leaves 1.5-20 cm. long, with slender but upwardly sometimes short petiole and (3) 7-21 opposite or often scattered, moderately distant or remote leaflets varying from linear-filiform and closely folded to flat and broadly oval in outline, acute or (when broad) obtuse or even subemarginate, the lateral ones articulate but sometimes obscurely so, the terminal one either similar to the rest and contiguous to the uppermost pair, or very commonly remote from them and then either jointed or tapering downward and decurrent into the rachis; peduncles slender, mostly incurved-ascending, (1) 2-13 cm. long, either shorter or a little longer than the leaf; racemes loosely, remotely, or in early anthesis sub- compactly 3-20 (25)-flowered, the flowers early spreading or somewhat declined, the axis ± elongating, 1-14 cm. long in fruit; bract membranous, ovate or lanceolate, (0.6) 1-4 mm. long; pedicels at anthesis ascending or arched outward, 0.8 2.7 mm. long, in fruit commonly twisted at base and irregularly spreading, contorted, or refracted, 1.2-3 mm. long; bracteoles commonly 0, minute when present; calyx 2.3-6 mm. long, strigulose with white, black, or mixed hairs, the symmetric disc 0.4-1 mm. deep, the campanulate tube 1.7-4.2 mm. long, 1.6-3 (3.5) mm. in diameter, the subulate or triangular-subulate teeth 0.5-2.6 mm. long, the whole becoming papery, marcescent unruptured; petals whitish or ochroleucous, often veined or suffused with dull lilac, sometimes all clear lilac or pink-purple, the keel- tip in any case maculate; banner recurved through 40-90°, broadly ovate- to suborbicular-cuneate, notched, 5.9—13 mm. long; wings 5.3—10.6 mm. long, the narrowly oblong to oblong-obovate, sometimes broadly obovate, obtuse or rarely truncate blades 4-7.5 mm. long, both incurved but the left one more abruptly so and its inner margin infolded; keel almost always a trifle longer than the wings, 5.9-10.7 mm. long, the blades 3.8-7 (8.5) mm. long, oblong-elliptic in the lower 2/3, thence abruptly incurved through 85—95 (exceptionally only 45)° into the triangular, commonly narrowly triangular to lance-acuminate, beaklike apex; anthers 0.3-0.6 (0.7) mm. long; pod pendulous, sessile or substipitate (the stipe, when present, less than 1 mm. long), the body in profile exactly linear, linear- oblong, or very commonly broadest below the obliquely triangular apex and then narrowed downward into the calyx and thus oblanceolate or linear-oblanceolate, 1.1-2.5 cm. long, 1.9-4 mm. in diameter, straight or a little arched downward (and often a trifle incurved distally, hence obscurely sigmoid), strongly compressed laterally either when young or permanently (the flat sides sometimes distended by the seeds and becoming low-convex at maturity), bicarinate by the salient but filiform sutures, the green, sometimes purple-speckled or -mottled, glabrous or strigulose valves becoming papery, brown or stramineous, faintly reticulate, not inflexed; dehiscence apical and downward, sometimes elastically, through both sutures, the valves coiling outward to expel the seeds; ovules 6—19; seeds ochraceous, brown, or pale greenish, nearly always purple-speckled, the purple spots sometimes very numerous and confluent into a deep plum-purple ground, the testa smooth or very sparsely pitted, scarcely lustrous, 1.8-2.9 mm. long.
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Discussion
A discursive account of the complex racial situation in A. miser has been published recently (Barneby, 1956, p. 478-484), and only a few remarks of a general nature seem called for in these pages. The weedy milk-vetch is one of the commonest astragali of the Rocky Mountains, locally abundant upward through the sagebrush foothills into the main forest belt; but only a few forms, because of the small size and usually dingy coloring of the flowers, make any conspicuous contribution to the flora. The species, a near relative of A. convallarius, resembles it closely in the form of the pod, although this is usually shorter. The loose tuft of basal leaves arising from a superficial root-crown or caudex, the nearly always more ample foliage, and the triangular or beaklike keel-tip quickly distinguish it. In the northern Rocky Mountains A. Bourgovii, especially when in flower only, is sometimes difficult to separate from purple-flowered forms of A. miser, but the few ovules and distinctly stipitate, ordinarily black-hairy pod are diagnostic.
The weedy milk-vetch is of great interest since it embraces some varieties with basifixed pubescence and others with hairs all or largely dolabriform, a situation duplicated in A. (Ervoidei) Kentrophyta. The transition from a strictly basal, through a basal but lateral, into a suprabasal point of attachment can be traced from hair to hair in A. miser var. praeteritus, as also in typical A. Kentrophyta. In the Old World the type of hair-attachment has traditionally, since the time of Bunge’s monograph, been accepted as a criterion of subgenera in Astragalus; obviously it can serve no such purpose in America.
There are conflicting reports as to the toxicity of A. miser; some forms at least must be dangerous locoweeds. In the Cache National Forest, Utah, it has been found responsible for the death of cattle on the range, and small quantities fed experimentally to sheep had fatal results (Wayne Binns, Veterinarian with U.S. Dept. Agr., Animal Disease and Parasite Branch, personal communication). According to Beath (in Ecology 17: 692. 1936), A. hylophilus (= probably our var. oblongifolius) is an important stock poison in parts of southern Wyoming (confirmed by C. L. Porter in herb., No. 3482, NY, RM. TEX). Beath found the species only on two similar geological formations (the Hanna and Bishop conglomerates) and suggested a correlation between toxicity and bedrock. According to my own observations in Montana, Utah, Colorado, and elsewhere, the various forms of A. miser occur on a great variety of soils, as already remarked by Graham (in Ecology 18: 171. 1937) of var. oblongifolius in the Uinta Basin. A collector of var. praeteritus (J. E. Schrauz 107, RSA, USFS) describes it as providing "good forage for cattle and sheep," and var. oblongifolius is often browsed, even where innocuous feed is plentiful, at least in the Colorado Rocky Mountains. Far northward var. serotinus has been stigmatized (Eastham 13,515, WS) as the cause of "more losses in livestock in British Columbia than all other poisonous plants combined." Evidently much remains to be learned concerning the poisonous races of A. miser. It seems probable, however, that the toxic principle varies in intensity from one population (or one variety) to another, and possibly also at different stages of growth.