476 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



81. Pods not 3-angled or arcuate (82). 



82. Walls of the pods mottled, the pods 15 to 30 mm. 



long 37. A. SUBCINEREUS. 



82. Walls of the pods not mottled (83). 

 83. Plant and pods white-sericeous. 



40. A. ARIDUS. 

 83. Plant and pods strigose or glabrate (84). 



84. Pods 5 to 11 mm. long, globose or nearly so, 

 less than 1 X A times as long as their greatest 

 diameter, sparsely strigose. 



44. A. THURBERI. 

 84. Pods 12 mm. long or longer, ovoid, 1H to 3 

 times as long as their greatest diameter 

 (85). 

 85. Pods erect, 12 to 15 mm. long. 



41. A. PALMERI. 

 85. Pods spreading or pendulous (86). 



86. Racemes surpassing the leaves; pods 

 more than 25 mm. long. 



35. A. ALLOCHROUS. 



86. Racemes shorter than the leaves; pods 

 not more than 25 mm. long. 



36. A. wootoni. 



1. Astragalus impensus (Sheld.) Woot. and Stand]., Contrib. U. S. 



Natl. Herbarium 19: 369. 1915. 



Astragalus viridis (Nutt.) Sheldon var. impensus Sheldon, 

 Minn. Geol. and Nat. Hist. Survey Bot. Studies 9: 118. 

 1894. 



Kentrophyta impensa Rydb., Torrey Bot. Club Bui. 32: 665. 

 1906. 



Kaibab Plateau and Grand Canyon, Coconino County (Jaeger in 

 1926, Eastwood and Howell 6413, Korstian and Baker 135), 3,500 to 

 8,000 feet, September. Western Colorado to eastern Oregon, south 

 to New Mexico, Arizona, and Nevada. 



Very different in appearance from any other of the Arizona Astra- 

 galus, with hard, almost woody, more or less prostrate stems, sharply 

 spine-tipped leaflets and stipules, and small axillary flowers. This 

 species is considered excellent for control of erosion. The Arizona 

 form is Kentrophyta coloradensis (M. E. Jones) Rydb., the type of 

 which was collected at Lees Ferry, Coconino County (Jones in 1890). 



2. Astragalus episcopus S. Wats., Amer. Acad. Arts and Sci. Proc. 



10: 346. 1875. 



Homalobus episcopus Rydb., Torrey Bot. Club Bui. 40: 53. 

 1913. 



Coconino County, 5,000 (to 8,000?) feet. Southern Utah and 

 Arizona. 



This and the 4 following species are characterized by more or less 

 rushlike appearance, narrow deciduous leaflets, and narrow pendulous 

 dehiscent pods. 



3. Astragalus lancearius A. Gray, Amer. Acad. Arts and Sci. Proc. 



13: 370. 1878. 



Northern Mohave County, at Beaver Dam, 1,800 feet (Palmer in 

 1877, the type collection) and west of Fredonia, 4,600 feet (Peebles and 

 Parker 14689). Southwestern Utah and northwestern Arizona. 



In the collection from near Fredonia the pods are much more obtuse 



