WHITE THISTLE 



Cirsium hookerianum Nuttall 



White thistles grow luxuriantly in the northern Rocky Mountains. 

 Their seeds, readily blown about by the wind, embrace every oppor- 

 tunity to obtain a foothold. Along the motor road between Banff and 

 Lake Louise they grow in great perfection, often four feet tall, with 

 numerous flower heads along the straight stem, commonly culmi- 

 nating in a rosette of many heads at the apex. The tender opening 

 flowers are much relished by the ponies, who do not seem to mind 

 the prickly bracts and leaves. Above tree line the plants are reduced 

 in size, often flowering when only six inches high. 



The white thistle is distributed from Montana northward to the 

 Canadian Rockies in Alberta and British Columbia. 



Our specimen grew near the summit of Vermilion Pass, Alberta, 

 on the motor road between Castle Station, on the Canadian Pacific 

 Railway, and the Columbia River Valley, at an altitude of 5,400 feet. 



PLATE IO3 



