Monographs Details: Astragalus pachypus var. jaegeri Munz & McBurney
Authors:Rupert C. Barneby
Authority: Barneby, Rupert C. 1964. Atlas of North American Astragalus. Mem. New York Bot. Gard. 13(1): 1-596.
Description:Variety Description - Characters as given in the key [Key: "Flowers a little smaller, the calyx-tube 3.7-4.3 mm., the banner 17-22 mm., the keel 10.7-12.6 mm. long; petals clear lemon-yellow when fresh; leaflets (15) 17-25 (27)."]; pedicels at anthesis 0.9-1.7 mm., in fruit 1.5-2.7 mm. long; calyx-tube 3.6-4 mm. in diameter, the teeth 1.8-2.8 mm. long; banner 7.2-9 mm. wide; wings 14-15 mm. long, the claws 5-6.5 mm., the blades 9-9.7 mm. long, 2.7-3.1 mm. wide; keel-claws 4.9-6.3 mm., the blades 6.7-7.4 mm. long, 2.7-3.1 mm. wide; anthers 0.6-0.8 mm. long.

Distribution and Ecology - Dry ridges and open sandy slopes in grassland and oak-chaparral, 1700-2500 feet, local, known only from west Riverside County, California, from the northwest foothills of the San Jacinto Mountains near Banning south to the Temecula River. —Map No. 57.—December to June.

Discussion:Narrowly endemic to the arid valleys just west of the desert in Riverside County, Jaeger’s bush milk-vetch differs from var. pachypus in a number of small characters, none of them important when considered severally, but distinctive enough in aggregate. The flowers slightly smaller in all average measurements and the many leaflets are the features most easily observed in dry specimens. In the living state the petals (as observed near Sage, Riverside County, in 1936) are clear lemon-yellow, strikingly different from the white or faintly roseate coloring of the typical form. However, since the white flower of var. pachypus turns ochroleucous or yellowish in drying, a useful distinction is lost in the herbarium. The one collection of var. Jaegeri known to Jepson (1936, p. 362) was not recognized as different from var. pachypus, although he particularly noted the locality (Dripping Springs, Peirson) as mystifying in relation to the known dispersal of the species around the head of San Joaquin Valley. The range of var. pachypus has since been extended east to the edge of the desert and north in the Coast Range to San Benito County, but it still conforms to an established distributional pattern, provided that var. Jaegeri is recognized as distinct.
Distribution:California United States of America North America|