" LAURELS '» 273 



have been very great. It occurs on the dry plains and foothills 

 of Arizona, New Mexico, southern and southwestern Colorado, 

 and southwestern Utah. Although animals do not devour the 

 plant under ordinary circumstances, they eat it when they are 

 very hungry. Poisoning usually occurs when stock come upon 

 a patch of milkweed after they have been driven some distance. 

 The plant is sometimes present in hay in sufficient quantity to 

 produce poisoning, and is also sometimes eaten as forage when 

 other plants are covered by snow. 



Whorled milkweed is a perennial with horizontal spreading 

 roots. It is very tough and difficult to eradicate. As the seeds 

 are winged, the plant is readily distributed. It grows abun- 

 dantly along railroads, on the banks of ditches, and in waste 

 places (Fig. 93). 



Obviously one who would prevent animals being poisoned 

 from milkweed should learn to recognize the plant and keep 

 hungry animals away from it. If stock must be driven over 

 areas infested by milkweed, either the plants should be cut and 

 burned, or the animals should be well fed before the drive is 

 begun. 



Oak (Quercus). — Although no clear-cut results have been 

 obtained from experiments, it is thought that Gambel oak 

 {Quercus Gambelii) and shinnery oak {Q. Havardi) are responsible 

 for most of the cases of so-called oak poisoning. An exclusive 

 diet of the young buds and leaves evidently causes trouble. If, 

 however, oak leaves form only a part of the feed, they are good 

 forage. When eaten alone they are constipating, and this may 

 produce illness or even death. Cattle appear to be the only 

 animals affected. 



Laurels " {Ericaceae). — Heavy losses of sheep from " laurel " 

 poisoning are not uncommon on western ranges where other 

 forage is scarce. These poisonous species may be mentioned : 

 Smooth menziesia {Menziesia glabella), which has caused serious 

 losses in sheep (Fig. 94); black " laurel " {Leucothoe Davisiae), 

 which is extremely toxic to sheep, found commonly in the 

 northern Sierras in California, but not widely distributed (Fig. 

 95); Labrador tea {Ledum glandulosum) , growing in the moun- 



