Astragalus argophyllus var. panguicensis

  • Title

    Astragalus argophyllus var. panguicensis

  • Author(s)

    Rupert C. Barneby

  • Scientific Name

    Astragalus argophyllus var. panguicensis (M.E.Jones) M.E.Jones

  • Description

    192c.  Astragalus argophyllus var. panguicensis

    Closely resembling the dwarfer states of var. Martini, commonly subacaulescent, the stems rarely developed and up to 5 (10) cm. long; hairs of the herbage narrowly to widely ascending or subappressed, up to 0.65—1.5 mm. long, silvery- silky; leaves 1.5-6 (8) cm. long, with 7-15 (17) oval-obovate, obtuse or very shortly acuminate and then subacute leaflets 2-9 mm. long; calyx 9-12 (14) mm. long, the tube 6.8-8.7 (10.6) mm. long, 2.8-3.4 mm. in diameter, the teeth 1.9-3.4 (4.2) mm. long; banner 5.6-8.6 (10) mm. wide; wings 14.2-17.1 (22.6) mm. long, the claws 8.4-9.4 (12.8) mm., the blades 6.8-8.7 (10.3) mm. long, 2-2.6 mm. wide; keel-claws 7.5-9.8 (12.7) mm. long, the blades 4.6—6.1 (8.3) mm. long, 2.5-3.4 mm. wide; pod lunately lance-ellipsoid or narrowly and very obliquely ovoid-acuminate, 1.5-2.7 cm. long, 5-8 (9) mm. in diameter, the surface of the valves concealed or nearly so by a dense coat of appressed and narrowly ascending, silvery hairs up to 0.5-0.75 mm. long—Collections: 17 (v); representative: Maguire 19,184 (WTU); Ripley & Barneby 4882 (CAS, RSA), 8566 (RSA, UTC), 8556, 8574 (RSA).

    Gravelly hillsides and benches in yellow pine forest, coming out into sagebrush flats, 6750-9300 feet, locally plentiful about the headwaters of the Sevier River in Garfield, Iron, and Kane Counties, east in Garfield County to the Henry Mountains, Utah; apparently also (with larger flowers) on the slopes of Mt. Emma, Uinkaret Plateau, Coconino County, Arizona.—Map No. 79.—May to July, exceptionally later.

    Astragalus argophyllus var. panguicensis (Jones) Jones, Contrib. West. Bot. 8: 5. 1898 ("Panguincensis"), based on A. Chamaeleuce var. panguicensis (of Panguitch Lake) Jones in Proc. Calif. Acad. Sci. II, 5: 671. 1895 ("Panguicensis").—"No. 6002m and 6023f, September 8, 1894, Panguitch Lake, Utah, 8400° alt... "—The specimen first cited not found at POM; lectotypus, Jones 6023f, POM!—A. panguicensis (Jones) Jones, Contrib. West. Bot. 10: 62, Pl. 4. 1902.

    Batidophaca sabinarum (of junipers, or "cedars," from the type-locality) Rydb. in N. Amer. Fl. 24 : 320. 1929.—"Type collected in Cedar Canyon, Iron County, Utah, July 19, 1920, A. O. Garrett R2660..."—Holotypus, NY!—Astragalus sabinarum (Rydb.) Barneby in Proc. Calif. Acad. Sci. IV, 25: 150. 1944.

    Until a few years ago the Panguitch milk-vetch had been collected seldom, consequently the nature and closeness of its relationship to A. argophyllus were difficult to estimate. In the summer of 1947 I found it to be quite frequent in the foothills of the Escalante Range in Garfield County, where it was possible to record a variation in flower-size extending up to and slightly overtaking that known in A. argophyllus var. Martini in the mountains shortly to the north. On the average, the pod of var. panguicensis is narrower and more strongly incurved than that of other forms of its species, and its ventral suture is usually more strongly depressed due to the curvature. It is variable in form, however, as are the fruits of all Argophylli, and except for its almost always denser and persistent silky vesture provides no infallible criterion. The variety is presumably a recent derivative of var. Martini, which has accumulated small differences in pubescence, in size of flower, and in shape of the fruit over a peripheral segment of the species-range.

    Long thought to be endemic to the headwaters of the Sevier River, var. panguicensis has been collected recently on Uinkaret Plateau north of Grand Canyon in Arizona. One gathering from this outlying station is to all appearances exactly typical (Cottam 14,049, CAS). Another (Cottam 13,690, CAS) from the same place has exceptionally large flowers suggestive of var. Martini, which has been collected not far distant on the Kaibab Plateau. Whether two distinct entities really exist in northern Arizona cannot be told from the material now at hand.

    Care must be taken to distinguish the Panguitch milk-vetch from A. castaneiformis, a closely similar species of which one variety, var. consobrinus, is sympatric with var. panguicensis in southcentral Utah. The dolabriform hair-attachment of A. castaneiformis is an everpresent clue to its identity at all stages of growth.