134 STOCK-rOISONING PLANTS OF MONTANA. 



Dawson, and Valley counties and in the Yellowstone Valley. It is a 

 smooth, erect plant, 2 to 3 feet high, with ovate leaves, the uppermost 

 of which have petal- like margins. The seeds of this plant have proved 

 nearly fatal to children who ate a few of them, and the juice is well 

 known to be poisonous to the skin of many persons, the effect being 

 somewhat like that caused by the oil of the ordinary poison ivy {Rhus 

 radicans) of the eastern United States. 



FIELD HORSETAIL, 



{Equhetiiin arvense L.) 



A rash-like, branching plant, with jointed stems from running root- 

 stocks, having sheaths at the joints and, when fertile, terminated by a 

 conical, spike-like fructification composed of shield-shaped, stalked 

 scales. The fertile stems are from 4 to 10 inches high, the sheaths 8 

 to 12 toothed. The sterile stems are slender and produce long, much- 

 branched, quadrangular branches. This plant occurs everywhere in 

 moist places across the continent, but is more abundant in the eastern 

 part of the country. 



A case of the poisoning of horses by eating the field horsetail was 

 reported to the United States Department of Agriculture from Con- 

 necticut in 1871, and one of horses and sheep from Vermont in 1899 

 and also in 1900. Cases are not, however, at all common in the United 

 States and the plant has not been laid under suspicion at all in Mon- 

 tana. It grows very commonly around Bozeman. 



Fifty grams of the more foliaceous male plants was gathered on June 

 6 and fed at 11 o'clock the same morning to a small rabbit weighing 

 somewhat less than a pound, which had been deprived of its breakfast. 

 It ate the plant readily and with apparent relish, all of it having dis- 

 appeared within four hours. The only symptom of distress noted dur- 

 ing the whole day was a decided thirst, which was made evident 

 especially at 3 o'clock when, after voiding a copious amount of urine, 

 the animal turned around and lapped it up again. The water then 

 offered was consumed in unusual quantity. On the next morning a 

 peculiar action of the jaws was noted, which seemed to indicate that 

 the mouth had been made sore by eating the harsh leaves. Inspection 

 of the mouth, however, showed no apparent abrasion. The rabbit was 

 otherwise perfectly well, and at 2 p. m. it readily ate some fresh plants 

 which were offered. Had the feeding been continued daily as a nearly 

 exclusive diet some harm, and possibly fatal results, might have 

 followed; for the experiments made in Europe show that a very simi- 

 lar species {E. palustre) is fatal to horses when hay contaminated with 

 it is fed to them in considerable quantit3^ The plant, if deleterious, 

 is evidentl}'^ so only on account of its harsh scouring action in the 

 mouth and intestinal tract. Meadow hay containing a large amount of 

 field horsetail should be fed sparingly. 



