Astragalus agrestis Douglas ex G.Don
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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(2): 597-1188.
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Family
Fabaceae
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Scientific Name
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Type
"Native of North America, near the Columbia River in fields."—Holotypus, formerly in herb. Lambert., not found at BM or OXF, apparently lost, but the identity known from the following reference.—A. Hypoglottis (3 Hook., Fl. Bor.-Amer. 1: 148. 1831, where
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Synonyms
Astragalus dasyglottis Fisch. ex DC., Astragalus hypoglottis var. dasyglottis (DC.) Ledeb., Astragalus goniatus Nutt. ex Torr. & A.Gray, Astragalus hypoglottis var. polyspermus Torr. & A.Gray, Astragalus agrestis var. polyspermus (Torr. & A.Gray) M.E.Jones, Astragalus virgultulus E.Sheld., Astragalus agrestis f. virgultulus (E.Sheld.) B.Boivin, Astragalus hypoglottis var. bracteatus Osterh., Astragalus agrestis var. bracteatus (Osterh.) M.E.Jones, Astragalus tarletonis Rydb.
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Description
Species Description - Slender, low, diffuse, or erect but then weak-stemmed and commonly supported by grasses, with an oblique or vertical taproot terminating in a knotty crown or shortly, less often widely forking subterranean caudex, the stems and herbage thinly strigulose-pilosulous with fine, straight, appressed or narrowly ascending hairs up to (0.35) 0.5-0.9 mm. long, sometimes nearly glabrous, rarely cinereous when young, the leaflets either glabrous or thinly pubescent above, the inflorescence villous-pilose; stems usually few, (4) 8-25 (30) cm. long, simple, leafless and subterranean for a space of (0) 1-9 cm., becoming stouter on emergence, either simple thereafter, or branched just above ground, or shortly branched or spurred at 1—2 nodes preceding the first peduncle, in open places forming close, leafy tufts, in meadows or shade becoming thin and lax; stipules (1) 2-10 mm. long, the lowest papery-scarious or early becoming so, smaller than succeeding ones, amplexicaul and connate into a bidentate sheath, the median and upper ones commonly pallid and submembranous at base, shortly connate, but produced into erect, ovate or lanceolate, mostly obtuse, foliaceous or submembranous but greenish free blades; leaves 2-10 cm. long, shortly petioled, with 13-21 (23) lanceolate, oblong-elliptic, oval, or rarely linear-oblong, retuse, obtuse, or rarely (in some upper leaves) subacute, flat, thin- or sometimes thick-textured (and then, when dry, dorsally corrugated) leaflets 4-18 mm. long; peduncles relatively stout, erect or incurved-ascending, 1.5-11 cm. long, either longer or shorter than the leaf; racemes densely 5-15-flowered, the erect or narrowly ascending flowers crowded into an ovoid, shortly oblong, or subglobose head, the axis not or scarcely elongating, 0.5-2 (2.5) cm. long in fruit; bracts membranous at base but herbaceous distally, lance-, linear-oblong, or elliptic and obtuse, more rarely lanceolate and subacute, 3-7 mm. long; pedicels erect or ascending at a narrow angle, at anthesis 0.5-1.5 mm. long, in fruit a trifle thickened but hardly longer, persistent; bracteoles 0; calyx (7.5) 8.5-12.5 mm. long, densely or sometimes thinly villous- pilose with straight and either ascending or spreading, or spreading and curly, black and white hairs mixed in varying proportions (rarely all of either color), the subsymmetric disc 0.7-1.5 mm. deep, the cylindric or deeply campanulate, or somewhat turgid and narrowly fusiform tube 5-7.8 mm. long, 2.6-3.4 (3.8) mm. in diameter, the erect, lanceolate or linear-lanceolate, equal or unequal teeth (2.5) 3-5 mm. long, the whole becoming papery-membranous, ruptured, marcescent; petals magenta-purple with white or pallid wing-tips, bluish-lilac, whitish faintly lilac-tinged, more rarely ochroleucous but then nearly always suffused with dull lilac when fresh; banner recurved through ±25°, oblanceolate, rhombic-oblanceolate or -elliptic, shallowly or deeply notched, (15) 17-22 mm. long, 5.6-8.5 (9) mm. wide; wings 15-18.5 mm. long, the claws 6-8 mm., the narrowly oblong or oblong-oblanceolate, obtuse or obliquely emarginate, straight or slightly incurved blades 9-12 mm. long, 1.7-2.6 (3) mm. wide; keel 11.4-14 mm. long, the claws 6-8 mm., the lunately half-elliptic blades 5-7 mm. long, 2.1-3 mm. wide, gently incurved through 70—90° to the bluntly triangular apex; anthers (0.5) 0.55-0.75 (0.8) mm. long; pod erect, obscurely stipitate, the glabrous stipe 0.3-1 mm. long, the body ovoid or oblong-ellipsoid, nearly straight, 7-10 mm. long, 2.8-4.5 mm. in diameter, truncate, abruptly rounded, or subcordate at base, abruptly contracted distally and cuspidate at apex, triquetrously compressed, carinate ventrally by the suture, the lateral faces flat or low-convex, the dorsal face widely but deeply sulcate, the green, thinly fleshy, at length papery valves densely silky-villous or -sub- tomentose above the glabrescent base with straight or curly, lustrous white hairs up to 1—2 mm. long, inflexed as a complete septum 0.8—1.4 mm. wide; ovules 14-22 (26); seeds smooth, brown, 1.2-2 mm. long.
Distribution and Ecology - Moist meadows and prairies, stream banks, grassy pockets on sagebrush hillsides, and cool brushy slopes, in the Great Basin sometimes on alkaline, summer- dry clay flats, ditches, and lake shores, but commonly in deep loamy soils, without apparent preference for bedrock, characteristic of low and middle elevations but ascending to 10,600 feet in the southern Rocky Mountains, widespread and common on the plains and in the foothills from central New Mexico to the upper Yukon Valley (reported of old from Alaska), west to interior Washington, Idaho, northeastern California, and the Sevier-Colorado divide in southwestern Utah, east to James Bay ± lat. 52° N. in Ontario, to southern Manitoba, western Minnesota, northern Iowa, and reported (Fernald, 1950) from Kansas; also widely dispersed in eastern and central Asia.—Map (in America) No. 78.—May to August, perhaps later northward.
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Discussion
In its American range the field milk-vetch, A. agrestis, is catholic in its choice of habitat, its one apparent necessity being plentiful moisture at the root during the period of active growth. It is found most commonly in low-lying meadows, on damp prairies, or along grassy stream banks where it is obliged to compete with other plants and tends to become relatively tall, erect, and weak-stemmed, with ample thin-textured foliage, and with peduncles surpassing the subtending leaf. Here and there, but with increasing frequency westward and southward from Montana, the plants are equally at home in more open places such as depressions on basalt plains, along roadside ditches where winter rain collects and settles, or on the margins of summer-dry lakes. In these and comparable sites the individual is generally of lower and more compact growth, sometimes truly dwarfed in strongly alkaline soils, while the peduncles become shorter and the leaflets smaller and of thicker texture. These, however, are no more than individual variants subject to environmental conditioning, and the flowers vary within the same size-limits irrespective of the plant’s stature. The color of the petals and of the calyx-hairs, and the length of the bracts, stipules, and calyx-teeth are all variable features in A. agrestis, but they are nowhere correlated and fail severally to conform with any recognizable pattern of dispersal. It is therefore not possible to maintain such segregates as A. Tarletonis, A. agrestis (sens, restr.), or A. virgultulus, supposedly distinguished by combinations of these characters.
The field milk-vetch is taxonomically isolated in our flora, but has several close relatives in Eurasia, notably A. danicus Retz. (= A. Hypoglottis auct., non L. emend. Lacaita). The latter closely resembles A. agrestis in habit of growth and in most fine details; but whereas the villous-pilose inflorescence of our plant contrasts with foliage merely strigulose or glabrescent, the leaves of A. danicus are thinly pilose with spreading or ascending hairs while the calyces are strigulose. Bracts, stipules, and calyx-teeth all are shorter on the average in A. danicus, but these seemingly separate features tend to vary together as though controlled by a common genic mechanism and thus constitute only one, and that an unimportant differential character. The range of A. danicus extends from western Europe into central Asia, where it overlaps that of A. agrestis to some extent, and there are indications of intergradation between the two in Altai. Very possibly Ledebour’s disposition of A. dasyglottis Fisch. as a variety of A. danicus (as A. Hypoglottis) will be confirmed.
The history of A. agrestis goes back to the earliest botanical explorers of western North America. Although it was unknown to Pursh in 1814, by 1838, the date of Torrey & Gray’s Flora, it had been collected by Douglas in Washington and Manitoba, by Drummond in Alberta, by Nuttall in Wyoming, and by Dr. James on the South Platte. These and other early gatherings were identified by Hooker, Gray, and Torrey as A. Hypoglottis or referred to a var. polyspermus, so named because the several-ovulate pod was believed to differ from that of European A. Hypoglottis, described erroneously by DeCandolle as two-seeded. Nuttall had recognized one of his own collections as A. dasyglottis and described another as A. goniatus, but these attempts to differentiate between superficially disparate forms were carried no further until many decades later. In Gray’s Revision (1864, p. 197) only a single, supposedly circumboreal "A. Hypoglottis" is recognized. Jones appreciated the differences between the European species and ours, for which he adopted (1923, p. 170) the long-forgotten A. agrestis Dougl. ex G. Don, a name which has remained intermittently current since. The first modern reference to the presence of the Asiatic species known as A. dasyglottis (of Fischer, not of Pallas) is apparently that of Gontscharov (1946, p. 258). A commentary on its history and bicentric dispersal has been published elsewhere (Barneby in Leafl. West. Bot. 9: 49. 1959), but it has been discovered since that the name A. dasyglottis taken up for the species common to Asia and America is a later homonym. The first A. dasyglottis dates back to Pallas’s monograph of 1800 and was a deliberate and even at the time illegal substitute for A. pentaglottis L ( = A. echinatus Murr.), to which Pallas subordinated A. Hypoglottis L. (probably meaning A. danicus Retz., not A. purpureus Lamk.) as a variety. Since A. dasyglottis Pall, was palpably superfluous and taxonomically indefensible from birth, it was passed over by DeCandolle (Prod. 2: 1825) when he came to publish A. dasyglottis Fisch. The Pallas name was taken up by Steudel (Nomencl., Ed. 2, 1: 160. 1840) as a synonym of A. pentaglottis, and is so quoted by Index Kewensis, thereby escaping the serious attention of modern authors (including Gontscharov and Barneby). It seems possible that the name A. dasyglottis, as used by Fischer on the label which reached DeCandolle and which passed into the literature through the pages of the Prodromus, was a sensu-name, not intended by Fischer as a proposition independent of A. dasyglottis Pall., even though it was so interpreted by DeCandolle. As mentioned already, Pallas construed A. Hypoglottis L. as a variety of his own A. dasyglottis, and a specimen of either species might easily have been distributed under the latter name.
So far as I have seen it in the field, A. agrestis is not a weedy astragalus, although sometimes found along ditches where it encounters the moist conditions needed for successful growth. However it has been reported as adventive in Boone County, Illinois (near Belvidere, Jones & Fuller, Vasc. Pl. 111. 273. 1956), and some of the outlying stations on record may have been opened up to the species by man-made changes in environment. Prof. C. L. Porter tells me that in the Rocky Mountains the flowers of A. agrestis are agreeably fragrant. In water meadows of western United States the plants are often browsed, but I have no report of A. agrestis as a loco-weed.
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Objects
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Distribution
New Mexico United States of America North America| Colorado United States of America North America| Utah United States of America North America| Nevada United States of America North America| California United States of America North America| Iowa United States of America North America| Nebraska United States of America North America| Wyoming United States of America North America| Idaho United States of America North America| Oregon United States of America North America| Washington United States of America North America| Montana United States of America North America| South Dakota United States of America North America| North Dakota United States of America North America| Minnesota United States of America North America| Ontario Canada North America| Manitoba Canada North America| Saskatchewan Canada North America| Alberta Canada North America| British Columbia Canada North America| Yukon Canada North America| Northwest Territories Canada North America|