Astragalus wingatanus
Rupert C. Barneby
43. Astragalus wingatanus
Usually slender and wiry, often only sparsely leafy, thinly strigulose with straight, appressed, or subappressed hairs up to 0.2-0.5 mm. long, the herbage green or pallid green, the growing tips sometimes canescent, the leaflets glabrous above; stems several or numerous, diffuse or incurved-ascending, 1.5-4 (6.5) dm. long, simple and subterranean for a space of (0) 1.5-15 cm., commonly branched divaricately or spurred at the first emersed nodes, flexuous or zigzag distally; stipules scarious or early becoming so, 1.5-5 (8) mm. long, somewhat dimorphic, those at the buried and lower exposed nodes connate through at least half and sometimes their whole length into a truncate or shortly bidentate sheath, the upper ones becoming narrower and successively less connate, the uppermost with lanceolate, subherbaceous blades united at base only or nearly free; leaves (1.5) 2.5-6.5 cm. long, shortly petioled or the uppermost subsessile, with 3-15 (17) linear, linear-oblanceolate, narrowly elliptic, or filiform, or (especially in some lower, rarely in all leaves) oblong-elliptic, either subacute, obtuse, or (when broad) shallowly retuse, flat or involute leaflets (2.5) 4-18 mm. long, the terminal one commonly longer than the last pair, the lateral ones sometimes reduced or even lacking in some upper leaves; peduncles strictly erect or incurved-ascending, rather stiff, (2) 3-9 cm. long; racemes loosely or remotely (5) 10-35-flowered, the flowers ascending at early anthesis, declined thereafter, the axis elongating, (3.5) 5-16 cm. long in fruit; bracts papery, ovate or lanceolate, 0.5-2 mm. long; pedicels at anthesis straight, ascending, 0.8-1.5 mm. long, in fruit either strongly arched out- and downward, or straight and abruptly divaricate, or deflexed, 1.5—3 mm. long; bracteoles 0—2, minute when present; calyx (2) 2.5—3.7 mm. long, strigulose with variably proportioned white and black, all white, or all black hairs, the subsymmetric disc 0.5—0.8 mm. deep, the campanulate tube (1.5) 1.6-2.6 mm. long, 1.2-1.8 (2) mm. in diameter, the subulate teeth 0.5-1.4 mm. long, the ventral pair often broadest and shortest, the orifice often oblique; petals either bicolored, lilac-purple with contrasting white wing-tips, or whitish with banner and keel-tip lilac-suffused or -veined; banner recurved through ± 50°, broadly rhombic-obovate or suborbicular beyond the short-cuneate claw, shallowly or deeply notched, 5.6—8 mm. long, 4—6 mm. wide; wings 4.3—7.1 mm. long, the claws 1.2—2.4 mm., the obovate, obliquely elliptic, or broadly oblanceolate, obtuse or obscurely erose-emarginate blades (3.1) 4—5.6 mm. long, 1.3—2.2 mm. wide, both incurved but the left one more abruptly so and its inner margin infolded, keel 3.5—5.4 mm. long, the claws (1.3) 1.7—2.5 mm., the half-obovate or nearly half-circular blades 2.3—3.2 mm. long, 1.3—2 mm. wide, incurved through 90—110 to the obtusely deltoid, sometimes obscurely porrect apex; anthers 0.3—0.45 (0.5) mm. long; pod deflexed or pendulous, subsessile or shortly stipitate, the stipe up to 1.7 mm. long but usually less than 1 mm. long or subobsolete, the body symmetrically or obliquely ellipsoid, oblong-ellipsoid, or somewhat clavately ellipsoid, straight or rarely a little incurved, (6) 9—15 mm. long, (2.5) 3—4.5 mm. in diameter, cuneate or cuneately tapering at base, abruptly acute and mucronulate at apex, strongly compressed and 2-sided when first formed but the valves somewhat distended by the ripening seeds and becoming low-convex, bicarinate by the prominent but slender sutures, these either equally convex-arcuate as seen in profile, or the dorsal one straight and the ventral one convex, the thinly fleshy, greenish, purple-speckled or -mottled, glabrous valves becoming papery, stramineous, delicately reticulate; ovules (4) 5-8; seeds dark brown, lustrous but more or less pitted and wrinkled, 2.8-3.6 mm. long.—Collections: 37 (viii); representative: W. A. Weber 4720 (CAS, SMU, TEX, WS); Ripley & Barneby 5353 (CAS, NY, RSA); Holmgren & Hansen 3336 (NY, WS, WTU); Barneby 12,774 (CAS, RSA).
Sandy clay hillsides, talus beneath sandstone cliffs, open flats in piñon- juniper woodland, and about oak thickets, 5000-7500 feet, widely distributed and locally plentiful in the Colorado Basin south of Tavaputs Escarpment, from Price River, Utah, east to the Grand River in Garfield County, Colorado, south to the Four Comers country and, becoming rarer, to the head of the Zuñi River in McKinley County, New Mexico, and the Navajo Reservation in northeastern Arizona—Map No. 16.—Mid-April to July, the fruit sometimes persisting into September.
Astragalus wingatanus (of Fort Wingate) Wats. in Proc. Amer. Acad. 18: 192. 1883 ("Wingatanus’’).—"At Fort Wingate, New Mexico (Dr. W. Matthews, 1882)."—Holotypus, GH! isotypi, some dated 1883, K, P!—Homalobus wingatanus (Wats.) Rydb. in Bull. Torr. Club 31: 563. 1904 ("wingatensiscorrected to "wingatanus" by A. Hell. in Muhlenbergia 1: 145. 1906).
Astragalus Dodgianus (Col. D. C. Dodge, apparently a friend of Jones) Jones in Zoe 3: 289. 1893.—"May 7, 1891, at Thompson’s Springs, Eastern Utah . .. "—Holotypus, collected by M. E. Jones, POM! isotypi, GH, NY!—Homalobus Dodgianus (Jones) Rydb. in Bull. Torr. Club 40: 52. 1913 ("Dodgeanus").—A. wingatanus var. Dodgianus (Jones) Jones, Rev. Astrag. 69, Pl. 1. 1923 ("Dodgeanus").
Astragalus acerbus (bitter, from the "very bitter, tealike taste") Sheld. in Minn. Bot. Stud. 1: 123. 1894.—"Collected near Glenwood Springs, Colorado, June [18], 1893, by Mr. DeAlton Saunders of the University of Nebraska."—Holotypus, MINN! isotypus, NY!— Homalobus acerbus (Sheld.) Rydb. in Bull. Torr. Club 32: 666. 1905. A. tenellus fma. acerbus (Sheld.) Macbr. in Contrib. Gray Herb., New Ser., 65: 35. 1922.
The Fort Wingate milk-vetch is variable in minor aspects of the pod, and so much so in the development of the leaves as to account, in great part, for the synonymy which has developed around the species. The pod varies from subsessile to distinctly stipitate, and in profile from symmetrically oblong-elliptic to almost half-elliptic, the sutures being nearly parallel or equally convex in the first case, the dorsal one straight and the ventral convex in the second. These variations occur independently of one another—to some degree, within populations of limited extent—and must be considered normal for the whole species. In strictly typical A. wingatanus the leaves have about five to seven pairs of elliptic to oblong leaflets, those of the lowest leaves tending to be broader than in succeeding ones. In arid environment, especially at the foot of sandstone buttes at low elevations in the valleys of the Price and Grand Rivers, and more rarely southward, A. wingatanus is represented by a xerophytic ecotype in which the lateral leaflets are linear or linear-filiform and reduced to 1-5 pairs, tending to become rudimentary, scattered, or even wanting in some upper leaves. The most junceous forms appear quite distinct at first sight from the leafier ones, but field experience and a full herbarium record have provided evidence of a gradual transition between the extremes. The typus of A. Dodgianus provides an example of few leaflets combined with oblique pods, that of A. acerbus a combination of symmetric pods with scanty foliage. If so desired these two forms might be treated collectively as A. wingatanus var. Dodgianus, although it is here preferred to treat them as two of a series of minor variants of the Fort Wingate milk-vetch.
The epithet Dodgianus was so spelled in the original publication and repeated in the same form by Jones in his seventh Contribution to Western Botany (1898, p. 636); it seems not to have been a misprint, although emended to Dodgeanus by Rydberg (1913, l.c.) and adopted in the corrected version in Jones’s Revision. The change of Watson’s epithet wingatanus to wingatensis is certainly illegitimate, even though the latter is stylistically preferable.
The close affinities of A. wingatanus have been assumed to lie with A. tenellus, and it may come as a surprise to find the two species assigned here to different sections. It is true that the pods are similar in form; but in its buried root-crown, general habit of growth, and elongated fruiting racemes, A. wingatanus has more in common with the Scytocarpi than with the typical Ervoidei. The pod of A. flexuosus var. Diehlii when, as often, it is somewhat laterally compressed, approaches that of the oblique forms of A. wingatanus, so that the latter is in reality less anomalous among the Scytocarpi than might be supposed. The clear line of relationship from A. tenellus leads through A. vexilliflexus into A. Kentrophyta, in a direction remote from A. flexuosus and its allies.
Mention has been made already of the resemblances between A. wingatanus and A. proximus of the preceding subsection, resemblances so many and so close that Jones believed the two species to be forms of one. While perfectly distinct, they are no doubt closely related. Other instances of pairs of related species differing in the direction of the pod’s compression are noted elsewhere in these pages.
The Fort Wingate milk-vetch was first collected in 1869, somewhere in New Mexico, by Edward Palmer (No. 67, NY).
References: [Article] Barneby, Rupert C. 1964. Atlas of North American Astragalus. Mem. New York Bot. Gard. 13(1): 1-596.