26 STOCK-POISONING PLANTS (>F MONTANA. 



in such seasons is apparently more nutritious than the longer, softer 

 grass of wet seasons, and stock keep in better condition when grazing 

 on the short grass than when supplied with large quantities of the 

 tall, soft grass. The chief fear of the stock grower in dry seasons is 

 that he will not be able to cut sufficient quantities of hay for winter 

 feeding. 



CONDITIONS UNDER, WHICH POISONING OCCURS. 



INFLUENCE OF HEAVY RAINSTORMS. 



Stockmen have observed for man}- years that during the spring 

 months poisoning is apt to occur after heavy rains. This may be said 

 to be a general belief of stock raisers and it is supported by numerous 

 observations. Various explanations have been ottered for this fact. 

 It has been suggested that certain plants ma}' ))e more poisonous when 

 wet with fresh rain or dew than under other conditions, but there 

 seems to ))e no ground for such a supposition. The explanation which 

 is most frequently proposed for this phenomenon is that stock when 

 feeding inunediatelv after heavy rainstorms are more apt to pull up 

 the roots of plants than when the range is dry. It is, of course, well 

 known that in the case of many poisonous plants the active principle 

 is located mostly in the I'oots and that large quantities of the leaves or 

 stems would have to be eaten in order to cause serious poisoning. 

 After a few days of dry weather the sod of prairie ranges becomes so 

 exceedingly hard and tough that it is a difficult matter to dig up plants 

 by the roots even with a trowel made for the purpose. While the 

 ground is in this state it is simply impossible for the roots of these 

 plants to be pulled up by stock in grazing. After working with plants 

 in a diy condition on the range one naturally comes to doubt whether 

 stock could pull up the roots of plants under any conditions. Obser- 

 vations upon this point after heavy rainstorms, however, will soon 

 dispel all doubt. The local rainstorms, usually accompanied by elec- 

 trical disturbances, are often almost in the nature of cloud-bursts and 

 are ordinarily very severe. The ground is so thoroughly soaked by 

 these storms that large underground bulbs and thick, tuberous roots 

 are easil}^ pulled out of the ground attached to the stems. It was 

 found that after such storms Zygademts bulbs could easily be pulled 

 up. There seems to be no reasonable explanation of poisoning being- 

 more frequent after rainstorms except this loosening of the roots of 

 poisonous plants. It is barely possible that storms accompanied by 

 winds may beat down the weeds and grass together, so that stock will 

 not distinsfuish between them so readilv as under drv conditions. 



