24 IP o s t e 1 8 1 a 



tain and Russian thistle. In dry places 

 occur numerous prostrate species, such 

 as Verbena bracteosa, purslane, knot- 

 grass, spurges and species of Amaran- 

 thus. In moist places such plants as 

 Rumex and Polygonum abound, and 

 with them numerous sedges. Among 

 the late flowering plants are the prickly 

 lettuce, dog-fennel, ragweeds, tall flea- 

 bane, asters, Iva, sunflowers, cone- 

 flowers and cockleburs. 



The plants just named are widely 

 distributed. They form an important 

 part of the flora not only of eastern 

 Colorado, but of the Mississippi basin 

 generally. Some are the common intro- 

 duced plants known everywhere in east- 

 ern North America, some are natives of 

 the Eastern States which have migrated 

 westward with man, some are western 

 representatives of genera well known by 

 other species farther east. 



