374 



WEED FLORA OP IOWA 



Woolly Thistle {Gi/rsium canescens Nutt.). 



Description. — ^Branching perennial, 2-4 ft. high, woolly through- 

 out, branches bearing single, medium-sized heads ; . stem angled, 

 white-woolly; leaves, radical, 8 in.-l ft. long, the division usually 

 2-lobed, prominently ribbed, ending in stout spines; stem leaves, 

 except the lower, 1-4 inches long, pinnatifid, the upper sessile, 

 slightly roughened, with a slight cottony down, the lower white- 

 woolly; heads 11^-2 in. high; bracts of the involucre somewhat 

 arachnoid; lower scales with a broad base, glutinous ridge, and 

 ending in a minutely serrated spine, inner scales long, attenuated, 

 tips straw-colored; flowers purple. 



Distribution. — This species is distributed from Mason City and 

 southwestern Minnesota, west to the Rocky mountains. It was 

 collected by Chas. A. Geyer in 1839 and described by Nuttall. The 



PlO. 219. 



Woolly Thistle (.Oirsium canescens). Common in western Iowa fields 

 and roadsides. 

 (Photographed by Quade.) 



