38 8TOCK-POIS0NING- PLANTS OF MONTANA. 



into the stomach, but are fatal if injected into tlie blood. The ditier- 

 ence in the fatal dose when injected hypodermically and when fed 

 varies somewhat according to the poison and also to the kind of animal 

 used. With strychnine, for example, the ratio between the fatal dose 

 given hypodermically and that given b^- wa}' of the stomach is one to 

 ten in sheep, one to five in horses, one to three in pig's, and one to two 

 in dogs. This ratio in the case of sapotoxin, a poisonous substance 

 found in many plants, is nearly one to one hundred in the case of ani- 

 mals having a healthy alimentar}^ tract. When the latter is ulcerated, 

 however, the sapotoxin is far more poisonous. This explains why it 

 is that some animals in a herd or pen are sometimes killed b}- eating a 

 certain plant, while others eat it to a certain extent with impunitj'. 



METHODS OF PREVENTION AND REMEDIES. 



DISPLACING POISONOUS PLANTS «Y FOKAOK PLANTS. 



The use of aggressive forage plants for the purpose of displacing 

 poisonous plants upon the range has been attempted on a small scale 

 in various parts of the State. The preliminary experiments with such 

 forage plants are being conducted l)y the Montana Experiment Station 

 and b}^ various stockmen with a view to determining whether such 

 plants are able to maintain themselves under the semiarid conditions 

 of the Western cattle ranges. The only forage plants which have 

 been used for this purpose are smooth brome grass {Bromus inermix) 

 and western wheat grass or "bluejoint'"' {Agnqryron, occldentale Scrib- 

 ner). Both of these grasses make a vigorous growth upon the ranges 

 of the plains and mountains. The smooth brome grass has been widely 

 distributed in the Western States in the hope that it might prove a 

 valuable pasture and meadow grass under semiarid conditions. Natu- 

 ralh% however, it attains a greater size and covers the ground more 

 completeh" when supplied with an abundance of moisture than when 

 growing in dry situations. 



Judging from the present conditions in Montana it will require sev- 

 eral years for the smooth brome grass to form a suificiently thick sod 

 to displace larkspur, death camas, or loco weeds, which are indigenous 

 to the locality. Under dry conditions the smooth l)rome grass seems 

 to cover the ground rather slowly. In many areas of this grass, where 

 it had been growing for two or three years, the stools were well sepa- 

 rated by considerable intervals of ])are ground. The bluejoint spreads 

 more rapidly from the root, and is usually more aggressive than the 

 brome grass. Apparently, however, bluejoint does not do well on 

 the dry ranges. The short-awned brome grass {Bron>u>< inarglnatus 

 Nees), a native species, is spreading rapidly in a number of localities 

 in various parts of the State. In some places this grass had already 

 displaced all other native plants and occupied the ground completely. 



