Astragalus pachypus var. pachypus

  • Title

    Astragalus pachypus var. pachypus

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Astragalus pachypus Greene var. pachypus

  • Description

    144a. Astragalus pachypus var. pachypus

    Characters as given in the key; pedicels at anthesis (1) 1.5-3 mm., in fruit (1.5) 2-5.5 mm. long; calyx-tube 4.3-5 mm. in diameter, the teeth (1.5) 2.7-4.3 mm. long; banner 9-14.5 mm. wide; wings 14.3-18 mm. long, the claws 5.4-7 mm., the blades 9.9—13 mm. long, 3—4.5 (5) mm. wide; keel-claws 5.5—7.1 mm. long, the blades 7.7-10.3 mm. long, 3.4-4.2 mm. wide; anthers (0.65) 0.7-1.1 mm. long. Collections: 39 (iii); representative: Clokey & Anderson 6693 (CAS, NY, POM, WS); C. B. Wolf 11,131 (CAS, NY, TEX); Elmer 3994 (NY, POM, WIS); L. S. Rose 38,172 (CAS, NY); Ripley & Barneby 5860 (CAS, RSA).

    Open hillsides and brushy flats, in gravelly clay or shaley soils, especially about shale or sandstone outcrops, sometimes on granites, 1650-6300 feet, locally plentiful, often with digger pine, in the foothills about the head of San Joaquin Valley in northern Ventura, extreme northern Los Angeles, southwestern Kern, and northeastern Santa Barbara Counties, California, extending east to the edge of the Mohave Desert about Ricardo, Kern County, and in Antelope Valley, Los Angeles County; isolated in the inner South Coast Range in San Benito County (Griswold Hills; Idria to Panoche).—Map No. 57.—March to June (July), the fruit long persisting.

    Astragalus pachypus (with thick stipe) Greene in Bull. Calif. Acad. Sci. 1- 157. 1885 -"Mountains of Kern County, California, June, 1884, Mrs. Curran."-Holotypus, collected at Bealville, Kern County, CAS! Brachyphragma pachypus (Greene) Rydb. in N. Amer. Fl. 24: 401. 1929

    The typical form of the bush milk-vetch, var. pachypus, is a handsome plant when newly come into bloom easily recognized by its stiff, striate stems whitened by a coat of parallel contiguous hairs by its distant, linear leaflets silvery-pubescent above and greenish or ashen beneath, and by the amply proportioned, firm-textured flowers which are clear white except m rare forms having a faint blush of rose or lilac at the base of the banner and wings The pod, which spreads horizontally at base but is brought distally into a vertical position by the inward curvature, is terete when first fully formed, the lateral compression being achieved by inward collapse of the fleshy valves coincident with a stiffening of the sutures.

    The var. pachypus is subject to little variation. Around the head of San Joaquin Valley and eastward to the desert edge, the ripe pod is relatively broad, about 5-7.5 mm. in diameter. The material from San Benito County (representative: Abrams 7959, NY, US; G. 5. Lyon 1645, CAS; Stebbins & al. 5077, CAS, DAV) has more slender fruits about 4—5 mm. in diameter, but the plants do not seem to differ significantly in other ways.