FLOWERING PLANTS AND FERNS OF ARIZONA 487 



"banks of Rio Virgen," possibly in Arizona {Fremont 44). Southern 

 Utah and northern Arizona. 



This and the 4 following species, also A. palans and A. mokiacensis, 

 are closely related and were treated as varieties of A. lentiginosus 

 Dougl. by M. E. Jones (Rev. North Amer. Astragalus. 123-127. 

 1923). 



58. Astragalus coulteri Benth., PL Hartw. 307. 1848. 



Astragalus arthu-schottii A. Gray, Amer. Acad. Arts and Sci. 



Proc. 6: 209. 1864. 

 Cystium coulteri Rvdb., Torrey Bot. Club Bui. 40: 50. 1913. 

 Cystium arthu-schottii Rydb., North Amer. Fl. 24: 409. 1929. 



Mohave County, northwestern corner {Tidestrom 9217), Beaver 

 Dam (Jones 5009a, Peebles 14767), "on the Colorado," probably in 

 Arizona (Schott, type collection of A. arthu-schottii). Western Arizona 

 and southern California. 



A. arthu-schottii seems to be merely a form of A coulteri with less 

 pubescent pods. 



59. Astragalus diphysus A. Gray, Amer. Acad. Arts and Sci. Mem. 



ser. 2, 4: 34. 1849. 



Cystium diphysum Rydb., Torrey Bot. Club Bui. 32: 659. 1906. 

 Cystium yuccanum (M. E. Jones) Rydb., North Amer. Fl. 24: 

 429. 1929. 



Almost through the State, up to 7,000 feet but usually lower, plains 

 and mesas, sometimes in open pine forests, common and abundant, 

 February to June, sometimes also late summer. Southern Utah, New 

 Mexico, and Arizona. 



Blue loco, rattleweed. A conspicuous plant because of the relatively 

 large size of all the parts. The flowers vary in color from whitish to 

 purple. The pods are occasionally mottled. This is one of the plants 

 known to cause loco disease, and it is reported to be poisonous to 

 horses, cattle, and sheep, in the order named. 



60. Astragalus macdougali Sheldon, Minn. Geol. and Nat. Hist. 



Survey Bot, Studies 1: 169. 1894. 



Cystium macdougali Rydb., North Amer. Fl. 24: 415. 1929. 



Apache, Navajo, Coconino, and Yavapai Counties, 4,500 to 7,000 

 feet, plains and mesas, sometimes growing with junipers, May and 

 June, type from Walnut Canyon, Coconino County (MacDougal 438). 

 Known only from Arizona. 



Closely related to A. diphysus, differing chiefly in the smaller 

 flowers and fruits. The pods occasionally are mottled. 



61. Astragalus agninus Jepson, Man. Fl. PL Calif. 577. 1925. 



Cystium agninum Rydb., North Amer. Fl. 24: 408. 1929. 



Near Yuma, about 200 feet, abundant in sandy soil on mesas, 

 March and April. Southwestern Arizona, southeastern California, 

 and northwestern Sonora. 



In flower this annual species might easily be mistaken for A. 

 coulteri, but the pods are much narrower and thicker-walled. Flowers 

 showy, violet purple, the herbage whitish pubescent. 



