Astragalus tephrodes var. brachylobus

  • Title

    Astragalus tephrodes var. brachylobus

  • Author(s)

    Rupert C. Barneby

  • Scientific Name

    Astragalus tephrodes var. brachylobus (A.Gray) Barneby

  • Description

    197a.  Astragalus tephrodes var. brachylobus

    Variable in habit within the limits given below; herbage greenish-cinereous to silvery-silky, the hairs varying from straight to incurved or sinuous, and from strictly appressed to loosely ascending or partly spreading, the longest up to 0.4—0.9 mm. long, the leaflets equally pubescent on both sides or nearly glabrous above; stems 0-8 cm. long; stipules 2.5-11 mm. long, villosulous, sparsely strigulose, or nearly glabrous dorsally; leaves 4—16 cm. long, with 11—27 (31) obovate-cuneate, oblanceolate, or rhombic-elliptic, rarely suborbicular, obtuse, acute, or emarginate leaflets (3) 4-17 mm. long; peduncles (4) 5-15 cm. long, shorter to much longer than the leaf; racemes 10—25 (35)-flowered, the axis (1.5) 2—8 cm. long in fruit; calyx 8.8-12.7 mm. long, pilosulous to loosely strigulose, more rarely villous, with mixed black and white hairs up to 0.5—0.85 (1.1) mm. long, the tube 7.1-10 mm. long, 3.4-4.8 mm. in diameter, the teeth 1.7-2.8 mm. long; banner (14) 18-24 mm., wings 15.4-22.7 mm., keel 14.7-20.1 mm. long; pod oblong- ellipsoid to lance-ellipsoid, more rarely ovoid-acuminate, 1.7—3 cm. long, 6—10 mm in diameter, the stiffly leathery or subligneous valves strigulose, pilosulous, or exceptionally glabrous; ovules 24—35.—Collections; 25 (viii); representative: Ripley & Barneby 5236 (CAS, NY, RSA); A. & R. Nelson 1959 (GH, NY); Barneby 12,626, 12,652 (CAS, RSA); Peebles 11,612 (CAS, POM).

    Open hillsides and stony flats in oak-chaparral, in juniper or yellow pine forest, or in arid grassland, on volcanic, granitic, or rarely sedimentary bedrock, mostly between 4300 and 6450 feet, but descending westward down to 3400 feet (and possibly lower along the Colorado River), common and locally abundant along the crest of the Mogollon Escarpment and through the hill-country immediately to the south, extending thence less commonly north to the south slope of the Kaibab Plateau (and to an isolated station in the Virgin Valley in Washington County, Utah), west to the Colorado River at Needles, California, and southeast around the edge of the Gila Basin to extreme westcentral New Mexico, there passing insensibly into var. tephrodes.—Map No. 81.—April to June, rarely later.

    Astragalus tephrodes var. brachylobus (Gray) Rydb. in Bull. Torr. Club 52: 154. 1925 (excluding the supposed "type," Palmer 102 in 1877). Astragalus curtilobus (with short calyx-lobes, a mistranslation of brachylobus) Tidest. in Proc. Biol. Soc. Wash. 48: 40. 1935, and op. cit. 50: 20. 1937, a legitimate substitute (non A. brachylobus DC., 1825).

    Astragalus pephragmenus (enclosed or girt, perhaps in allusion to the salient engirdling sutures of the pod) Jones in Zoë 4: 268. 1893.—"... on the summit of the Pinal Mountains, Arizona, May 26, 1890."—Holotypus, labeled "crest of the Pinals on road to Tonto Basin," POM! isotypi, GH, TEX, US!—A. argophyllus var. pephragmenus (Jones) Jones, Rev. Astrag. 208, Pl. 47. 1923. Xylophacos pephragmenus (Jones) Rydb. in Bull. Torr. Club 52: 151. 1925.

    Astragalus remulcus (tow-rope, the allusion obscure) Jones in Proc. Calif. Acad. Sci. II, 5: 658. 1895.—"Rusby, no. 576, Bangharte’s Ranch, Arizona, May, 1883 ... "—Holotypus, US! isotypus, NY!—Xylophacos remulcus (Jones) Rydb. in Bull. Torr. Club 52: 153. 1925.

    Astragalus intermedius (intermediate, supposedly between A. amphioxys and A. Bigelovii) Jones in Proc. Calif. Acad. Sci. II, 5: 656. 1895.—"Arizona, Palmer. Type in National Herbarium."—Lectotypus, the flowering element of the type-sheet, US! The pods in a package associated with the holotypus represent Oxytropis Lambertii var. Bigelovii!—A. phoenicis (of Phoenix, Arizona) Jones, Contrib. West. Bot. 8: 12. 1897 ("Phoenicis"), a legitimate substitute (non A. intermedius Kar. & Kir., 1842).

    Xylophacos lenophyllus (soft-leaved) Rydb., FI. Rocky Mts., Ed. 2. 1126. 1922.—"Type collected in the vicinity of Flagstaff, Ariz., MacDougal 27."—Holotypus, NY! isotypi, GH, POM!

    The ashen milk-vetch, A. tephrodes, is the commonest member of its section in Arizona, and over the central mountainous portion of the state the var. brachylobus is the characteristic astragalus of its type. At its northern limit the range of the variety slightly overlaps that of the related A. argophyllus, from which it may be distinguished by its slightly more numerous pairs of usually bicolored leaflets and by the longer and looser racemes. The pubescence-phases of var. brachylobus, however striking at first encounter, are no more than minor variants. The main types are as follows:

    M. v. 1. Hairs all straight and appressed (var. brachylobus, sens. str.). Range of the variety.

    M. v. 2. Hairs as in var. brachylobus, but the pod glabrous or early glabrate (A. remulcus). Yavapai County, Arizona, especially in the upper Verde Valley; the flowers sometimes of exceptionally brilliant purple (Barneby 12,660, RSA).

    M. v. 3. Hairs spreading, largely straight, the calyx villous, the pod ± hirsutulous (A. pephragmenus). Gila County, Arizona, and vicinity. The herbage varies in the same colony from greenish-cinereous to silvery.

    M. v. 4. Hairs spreading and incurved-ascending, fine and ± sinuous (X. lenophyllus). In pine forest, southern Coconino County, Arizona.