Although its precise range is unknown it is typically a southwestern 

 plant, and is known to occur in Colorado, western Texas, New Mex- 

 ico, Arizona, and Mexico; it also occurs on San Nicolas Island, off 

 the southern California coast. 



Although Old World and South American species of Stipa are 

 poisonous to domestic livestock, yet, so far as is known, sleepygrass 

 is the only species in the United States known to be poisonous to 

 livestock. While scientific analyses have thus far failed to uncover 

 any poisonous principles in sleepygrass, its narcotic effect has long 

 been recorded by many credible authorities. It is reported chiefly 

 as affecting horses, but also causes sleepiness in cattle and sheep, and 

 interferes with animal locomotion somewhat as does loco poisoning. 

 The narcotic influence is usually only temporary but, in some cases, 

 has been reported to last 48 hours and occasionally to be fatal. 1 

 Marsh and Clawson 2 report: 



The grass has been shown by experimental feedings to produce a narcotic 

 effect on horses. * * * While it may produce profound slumber, it does not 

 cause death. Cattle showed no effect from the plant, and sheep, although 

 slightly affected, did not show the typical symptoms of drowsiness. 



The degree of narcotism depends upon the amount of grass eaten, 

 which, in turn, is no doubt influenced by the scarcity of more 

 palatable forage. Apparently sleepygrass produces different effects 

 in different localities under similar conditions and utilization. 

 Marsh and Clawson (op. tit.} state that 



definite cases of sleepygrass poisoning have been reported from only two 

 general localities, the Sacramento and the Sierra Blanca Mountains in Otero 

 and Lincoln Counties, New Mexico. 



On the other hand, in various New Mexico and Colorado localities 

 this grass is eaten by livestock without any apparent narcotic effect. 1 

 Although it has been reported * that sleepygrass loses its poisonous 

 properties when dried, Marsh and Clawson (op. cit.) state that 



the green and the dry plant are about equally toxic if allowance is made for 

 the loss of moisture in the dry plant. 



Crawford 3 calls attention to some species of Stipa on the high 

 plateaus of Argentine Republic which contain a glucoside which, 

 when split up. yields hydrocyanic acid. He suggests the possibility 

 that some North American species, particularly sleepygrass, may 

 also on occasion yield hydrocyanic acid. 



Sleepygrass is low in palatability but is sometimes grazed closely 

 by cattle and horses in the absence of other more palatable forage. 

 Wooton and Standley (op. cit.} state that animals brought into the 

 region will consume it unless restrained. 



This species produces an abundant supply of seed which results in 

 satisfactory reproduction. It sometimes spreads over heavily grazed 

 ranges after the better grasses have succumbed, but is not aggressive 

 when in direct competition with them under controlled grazing. 



1 Wooton, E. O.. .and Stniullpy. P. C. FLORA OP NEW MEXICO. U. S. Natl. Mus., Contrib. 

 U. S. Natl. Herbarium 19, 794 'pp. 1915. 



2 Marsh. C. D., and Clawson. A. B. SLEEPY GRASS (STIPA VASEYI) AS A STOCK-POISONING 

 PLANT. U. S. Dept. Agr. Tech. Bull. 114, 20 pp., illus. 1929. 



3 Crawford, A. C. NOTES, MAINLY BIBLIOGRAPHICAL. ON TWO AMERICAN PLANTS SLEEPY 

 GRASS AND CREOSOTE BUSH. Pharm. Rev. 26 : 230-235. 1908. 



