Astragalus fucatus

  • Title

    Astragalus fucatus

  • Author(s)

    Rupert C. Barneby

  • Scientific Name

    Astragalus fucatus Barneby

  • Description

    41. Astragalus fucatus

    Perennial but sometimes flowering the first season, variable in stature, strigulose nearly throughout with straight, appressed or subappressed hairs up to 0.250.4 (0.6) mm. long, the stems commonly silvery-canescent, the herbage cinereous or greenish, the leaflets green and glabrous above; stems 1—several, diffuse and ascending, (0.4) 0.7—3 (exceptionally up to 7) dm. long, naked and subterranean for a space of (0) 1—4 cm., thereafter simple or (when robust) spurred or branched at 1—3 (5) nodes preceding the first peduncle, floriferous upward from below the middle, flexuous or zigzag distally; stipules (1) 1.5-4 (5.5) mm. long, the lowest amplexicaul and connate into a low, papery, collar-like (eventually fragile and easily ruptured) sheath, the rest fully or nearly amplexicaul but free or only obscurely connate, with broadly deltoid to lance-acuminate, subherbaceous or firmly papery, erect or recurved blades; leaves 3.5-10.5 (13) cm. long, all petioled but the upper ones shortly so, with 9-17 distant, narrowly oblong-oblanceolate or linear-oblong, obtuse or emarginate, involute or conduplicate, rarely flat leaflets 4—20 (25) mm. long; peduncles 1—4 (6) cm. long, racemes loosely 9—22 flowered, the flowers at first ascending but horizontal or declined in age, the axis somewhat elongating, (1.5) 2—5 (8) cm. long in fruit; bracts submembranous, triangular- lanceolate, 0.8-2 mm. long; pedicels at anthesis slender, ascending, 0.7-1.4 mm. long, in fruit thickened, recurved, 1—2 (3.5) mm. long; bracteoles 0, rarely a minute scale; calyx 3.3-4.6 mm. long, silvery-strigulose with white hairs, the sub- symmetric disc 0.7-1 mm. deep, the tube 2.4-3.3 mm. long, 2.1-2.6 mm. in diameter, the broadly subulate or triangular teeth 0.8-1.5 mm. long; petals reddish- or magenta-purple, the pale-eyed banner striate; banner abruptly recurved through ± 90°, broadly ovate-cuneate to rhombic-flabellate, 6.4-8.2 mm. long, 5.1-7.2 mm. wide; wings (1.1 mm. shorter to 0.4 mm. longer than the banner) 6.8-7.5 mm. long, the claws 2.1—2.6 mm., the elliptic-oblanceolate, obtuse, gently incurved blades 4.8-5.9 mm. long, 1.8-2.5 mm. wide; keel 6-7.2 mm. long, the claws 2.1—2.8 mm., the lunately half-elliptic blades 4.2—5 mm. long, 1.7—2.3 mm. wide, incurved through 80—90° and distally contracted into a triangular, subacute, slightly porrect, beaklike apex; anthers 0.4—0.55 mm. long; pod horizontally spreading or declined, sessile, broadly and plumply ovoid, obovoid, ovoid-ellipsoid, or subglobose, greatly inflated, 1.7-2.8 (3.2) cm. long, 1.2-2.2 cm. in diameter, contracted at base into a broadly obconic neck 0.6—2 mm. long and at apex into a deltoid, laterally compressed beak 0.8-2.5 mm. long, otherwise a trifle obcompressed, shallowly sulcate ventrally, the thin, brightly mottled valves becoming papery, delicately cross-reticulate and somewhat lustrous, loosely strigulose with short, subappressed or incurved-ascending hairs; ovules 21-32; seeds brown or olivaceous, often minutely purple-speckled, dull, smooth, (1.5) 2-3.3 mm. long.— Collections: 24 (ii); representative: Peebles & Smith 13,371 (ARIZ, CAS, NY); J. T. Howell 24,710 (CAS); Barneby 13,097 (CAS, GH, NY, RSA, US); Holmgren & Hansen 3444 (NY).

    Sandy plains, desert washes, sometimes on dunes or in dunelike hollows under cliffs, associated with red sandstones, 4500—6200 feet, locally plentiful along the lower San Juan River in San Juan County, Utah, extending north to the Colorado River in extreme eastern Garfield County, and east just into northwestern New Mexico and adjoining Colorado, and along creeks flowing south and west into the Little Colorado River in eastern Coconino, Navajo, and Apache Counties, Arizona.—Map No. 15.—May to July, the fruit sometimes persisting into September.

    Astragalus fucatus (painted, of the mottled pod) Barneby in Leafl. West. Bot. 9: 89. 1960.—"Arizona: near Hotevila, Navajo County, 6200 ft., June 8, 1937, Peebles 11,392."— Holotypus, Peebles 13,392 (!), CAS, isotypi, NY (labeled "5 miles w. of Oraibi"), US!—A. subcinereus sensu Jones, Rev. Astrag. 106, pro parte, exclus. syn. 1923. Phaca subcinerea sensu Rydb. in N. Amer. Fl. 24: 351. 1929; non A. subcinereus Gray.

    When christened A. fucatus the Hopi milk-vetch was new in name only, being substantially the A. subcinereus of Jones’s Revision and of the floras covering its range of dispersal. It is precisely, as shown by his annotations (NY), the Phaca subcinerea of Rydberg (1929). Reevaluation of the typus of A. subcinereus Gray showed that it represents a form of A. Sileranus Jones, and consequent shift of epithets left the present species without a name. The point is raised again under A. subcinereus (q.v.).

    Despite the fact that Jones placed A. fucatus and A. subcinereus in different sections of Astragalus, the two species are closely related and share the subterranean root-crown, connate lower stipules, and persistent pod of sect. Scytocarpi. It is only in the pod’s inflation that either resembles the Inflati or so-called phacas. The differently shaped keel-petals, generally larger or at least relatively broader pod, straight appressed vesture, and more numerous ovules are the features useful in distinguishing A. fucatus from its close kin. In addition, the plants are commonly of more open and wiry growth-habit than A. subcinereus, the leaflets are comparatively narrower and more distantly spaced along the rachis, and the whole appearance suggests a more harshly xerophytic habitat. The flowers of A. fucatus are reddish-purple when fresh (although the color fades rapidly in dried specimens); those of A. subcinereus are whitish or ochroleucous, faintly lilac-tinged or veined with dull brownish-purple.