456 Thirty-first Annual, Report 



similar forage plants were tall enough to be grazed. Naturally, 

 stock ate the succulent poison plant growth in preference to dry, 

 weathered grass stems. During this spring season, no less than 

 thirty complaints of stock being affected, or dying, from eating 

 poison plants were received from southern Arizona, and a con- 

 siderable number from central and northern Arizona. The follow- 

 ing were the more important of these poison plants ; spreading loco 

 (AragaUus nothoxus) ; Thurber's loco (Astragalus Thurheri) ; hairy 

 loco (Astragalus Bigelozvii) ; tall loco (Astragalus diphysus and 

 Astragalus diphysus MacDougali) ; purple loco (AragaUus Lamberti) ; 

 blue larkspur (Delphinium scaposum) ; prairie larkspur (Delphinium 

 campormn) ; and death camas (Zygadenus elegans). 



At Patagonio, Elgin, and certain other localities, the loco poi- 

 soning was quite dift'erent from that ordinarily observed. Stock 

 would become weak in the back, break down, and to a great extent 

 lose the power of their hind legs. Stockmen call this "tottering 

 loco." The plant causing this disease is believed to be a smpJl 

 loco weed which grows low and spreads out on the ground. It is known 

 botanically as AragaUus nothoxus. Commonly it is abundant enough 

 in places to form a nearly continuous growth, particularly in de- 

 pressions on the prairies. This plant was more often reported by 

 stockmen during the past spring as causing loco among stock than 

 all the other varieties of loco in southern Arizona combined. Dr. 

 C. D. Marsh, the Government poison plant specialist, visited Ari- 

 zona during the latter part of March and April to study the 

 situation. 



STUDY OF ARIZONA GRASSES 

 The writer devoted the major part of his time in Experiment 

 Station work for the year to a comprehensive study of the grasses 

 of the State. This work is concerned with the identification, di.s- 

 tribution, relative abundance, and economic value of our grasses 

 and forage plants. As far as possible, all the grasses in the State 

 growing wild, or without cultivation, are included in this study. 

 The grass flora of Arizona is relatively large and diversified and 

 includes a large number of Mexican and South American species. 

 A small amount of work remains to be done on this study before 

 the manuscript can be completed and submitted for publication. 



WORK AT FLAGSTAFF 



Beginning with the middle of July, the writer spent seven 

 weeks at Flagstaff, Arizona. Most of this time was given to in- 

 struction work in the University Summer School at the Flagstaff* 



