Astragalus Wootoni var. Wootoni

Variable as described for the whole species, except as limited by the key; leaflets (7) 11-19; pod strigulose.—Collections; 152 (x); representative: Munz 16,336 (CAS, POM, WS); Jones 3800 (NY, OB, POM), 4424 (NY, OB, POM, TEX); A. & R. Nelson 2061 (NY, WS); Ripley & Barneby 7577, 10,322 (CAS, RSA); McVaugh 7942 (SRSC, SMU, TEX); Tracy & Earle 339 (ND, NY, TEX); E. J. Palmer 31,037 (CAS, MO); T. & E. Frye 2323 (NY); E. Palmer 246 in 1908 (MICH, NY, US).

Plains, hillsides, and valley floors, in dry sandy or gravelly soils of varied composition, but apparently commonest on volcanic and granitic bedrock, more rarely on sandstone or limestone, sometimes locally abundant on semistabilized dunes or in disturbed sandy alluvia along highways, 2250—7300 (on the upper Rio Grande up to 8400) feet, in Larrea or sahuaro desert, desert- and mesquite- grassland, northward with sagebrush and juniper, widely dispersed and common, northern New Mexico west from the upper Pecos across northern Arizona south of the Colorado River to the extreme eastern Mohave Desert in eastern San Bernardino County, California, south and southeast to northeastern Sonora, Durango, Chihuahua, and trans-Pecos Texas.—Map No. 119.—March to July, sometimes again in late summer and fall.

Astragalus Wootoni (Elmer Ottis Wooton, 1865—1945, distinguished interpreter of the flora of New Mexico) Sheld. in Mum. Bot. Stud. 1: 138. 1894 ( wootoni ). Collected near Las Cruces, New Mexico, May, 1892, by Professor E. O. Wooton. No typus found (but perhaps overlooked) at MINN; presumed isotypus, collected in the foothills of the Organ Mountains. Dona Ana County, May 15, 1892, NY!—Phaca Wootoni (Sheld.) Rydb. in N. Amer. Fl. 24: 350. 1929. A. Wootoni var. typicus Barneby in Amer. Midl. Nat. 41: 498. 1949.

Astragalus playanus (of desert playas) Jones, Contrib. West. Bot. 8: 6. 1898.—"The types are the specimens of the writer’s collection of 1884 from El Paso, from New Mex. and Ariz. and all specimens referred to in Cont. vii 637 [i.e., in Proc. Calif. Acad. Sci. II, 5: i.e.] under triflorus... "—Lectotypus (Barneby, 1941, p. 498), collected at El Paso, Texas, Jones in 1884, POM!—A. triflorus var. playanus (Jones) Jones, Rev. Astrag. 106. Pl. 11. 1923.

Phaca Tracyi (Samuel Mills Tracy, 1847-1920, plant breeder, agronomist, mycologist) Rydb. in N. Amer. Fl. 24: 351. 1929.—"Type collected on Toyah Creek, western Texas, April 21, 1902, Tracy & Earle 78... ’’—Holotypus, NY! isotypi, ND, NY, MO, TEX, US!— Astragalus Tracyi (Rydb.) Cory in Rhodora 38: 406. 1936.

Astragalus triflorus sensu Gray in Pl. Wright. 2: 45. 1853 & in Proc. Amer. Acad. 6: 214. 1864, pro parte, exclus. syn. Kunth., basionym., et specimine Coulteri; sensu Torr., Bot. Mex. Bound. Surv. 56. 1859; et auct. al. bor.-amer.; non A. triflorus (DC.) Gray, sens. strict., nec Phaca triflora DC.

With one important exception the typical form of the Wooton milk-vetch is the only astragalus within its area of dispersal in which flowers as few and nearly as small are combined with pods at once greatly inflated, sessile, deciduous, and unilocular. The exception is A. allochrous, which is found over considerable areas in the Southwest, sympatric and in places apparently confluent with it. The ideal differences have been stressed above in the sectional key, but cf. the discussion of A. allochrous for a more discursive account. At the edge of its range the Wooton milk-vetch approaches that of several related and morphologically similar species: in Coconino County, Arizona, the rare A. endopterus, distinguished by its few (7-11) leaflets and many-ovulate pod with an extraordinarily broad funicular flange within; in the Mohave Desert, California, and extreme western Arizona, A. nutans and A. insularis var. Harwoodii, which differ from the nearly sympatric phase of A. Wootoni in their purple flowers and strongly oblique, prominently beaked fruits; and in northern New Mexico, A. cerussatus, easily recognized in practice by its villosulous herbage and narrowly septiferous pod. Other close relatives of A. Wootoni are the larger-flowered A. aquilonius of eastcentral Idaho, the almost glabrous A. Wardi of Utah, and A. Gilmani endemic to the Death Valley region. Among the Inflati only one other, A. insularis var. quentinus, localized on and near the Pacific Coast of northern Baja California, is characterized by a subsymmetric, nearly beakless pod, but this differs in its acute leaflets, shorter calyx-teeth, and few (8-10) ovules.

The var. Wootoni was first collected in the summer of 1852 by Charles Wright, whose specimens (No. 1361) are labeled alternatively "New Mexico" or "Sandy banks of the Rio Grande below El Paso," either in Texas or possibly in Chihuahua, where Josiah Gregg encountered it shortly afterward. This material was interpreted by Gray (Pl. Wright., l.c.) as conspecific with the Mexican Phaca Candolliana Kunth, which had previously been equated by DeCandolle with his own Peruvian P. triflora', and the name A. triflorus persisted in the North American literature up to the time of Jones’s Revision (1923). The Wright gathering was among the elements referred to obliquely by Jones when he described A. playanus.