PRAIRIE THISTLE 



Cirsium undulatum (Nuttall) Sprengel 



We rarely saw the prairie thistle in perfection. Our horses gra2;ed 

 on the mountain side back of our camp, and every plant to which 

 they had access was denuded of its flowers as soon as they opened. 

 Fortunately, a wire fence protected the garden at Radium Hot 

 Springs, and under this protection we found a good specimen. 



The plant is a picturesque one. The large purple flowers are very 

 sweet and attract many insects to their feast of nectar. The leaves are 

 very prickly and much waved, so that it is sometimes called wavy- 

 leaved thistle. We marveled that the apparently tender lining of the 

 horses' mouths was not injured by the stiff prickles. 



Prairie thistle ranges from Michigan to Arizona and British Co- 

 lumbia. 



The sketch was made from a plant that grew near Radium Hot 

 Springs in the Columbia River Valley, British Columbia, at an alti- 

 tude of 3,500 feet. 



PLATE 309 



