Astragalus amphioxys var. vespertinus

  • Title

    Astragalus amphioxys var. vespertinus

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Astragalus amphioxys var. vespertinus (E.Sheld.) M.E.Jones

  • Description

    222c.  Astragalus amphioxys var. vespertinus

    Habit of var. amphioxys, but the flowers a little larger, and the petals less strongly graduated; calyx-tube 8.8—13.2 mm. long, 3.8—5.2 mm. in diameter, the teeth 1.3-3 mm. long; banner 23-27 (28) mm. long, 7.8-12.7 mm. wide; wings 21.5-25 (26) mm. long, the claws 9.8-13.4 mm., the blades 12.2-16.3 mm. long, 2.5—4.2 mm. wide; keel 19—23.6 mm. long, the claws 10.2—13.4 mm., the blades 8.6-12.2 mm. long, 3.2-4.4 mm. wide; pod ± 3-3.5 cm. long, gently incurved; ovules 50—70 (averaging ± 60).—Collections: 28 (vi); representative. Ripley & Barneby 8577 (RSA, UTC); Barneby 12,751 (CAS, RSA); Jones 24,430 (CAS, POM); W. A. Weber 3335 (CAS, TEX); J. T. Howell 24,729 (CAS, RSA); Holmgren 3250 (NY, WS, WTU).

    Sandy valley floors, ledges under cliffs, and gravelly hillsides, in sagebrush or juniper forest, mostly on sandstone, 4300—5900 (6300) feet, locally plentiful within the Colorado Basin, south of Tavaputs Escarpment, southwestern Colorado and southeastern Utah, extending feebly west to the Grand Canyon and Kanab Plateau in northwestern Arizona.—Map No. 92. April to June.

    Astragalus amphioxys var. vespertinus (Sheld.) Jones, Rev. Astrag. 215. 1923, based on A. vespertinus (western) Sheld. in Minn. Bot. Stud. 1: 150. 1894.—"Collected near Grand Junction, Colorado, May, 1892, by Miss Alice Eastwood."—Holotypus, Eastwood 6109, MINN! isotypi, MO, NY!—Xylophacos vespertinus (Sheld.) Rydb. in Bull. Torr. Club 32: 662. 1905.

    The var. vespertinus is poorly characterized and flowers are required for its identification. These possess a subtly individual aspect, the petals being longer in proportion to the calyx than in var. amphioxys and less strongly graduated. A count of ovule-number in a random selection of 30 flowers showed a possibly significant higher average in var. vespertinus, although the ripe pod is no longer or larger.

    Two interesting but unfortunately meager collections from the Grand Canyon (Grand View Trail, Eastwood 5711, 5712, CAS) were mentioned in the preliminary revision (Barneby, 1947, p. 440) as representing a variant of var. amphioxys, but on account of the elongate keel- petals (± 21 mm. long) are more appropriately considered under var. vespertinus. The plants are remarkable for their slender growth-habit, thin pubescence of hairs short for the species as a whole (up to 0.3-0.7 mm. long), few (mostly 7-9) leaflets, and long fruiting pedicels (2.7—4 mm. long). More material is needed for adequate analysis.