402 



WEED FLORA OF IOWA 



Blue Lettuce (Lactuca pulchella (Pursh.) DC.). 



Description. — Perennial plant, deep-rooted, pale or glaucous; 

 stem simple, about 1 foot high; leaves sessile, oblong or linear- 

 lanceolate, glabrous, entire, or lower leaves somewhat pinnatifid; 

 racemose heads large, erect; peduncles with scaly bracts; bracts 

 of involucre imbricated in 3-4 ranks ; flowers blue. 



Distribution. — Northern Michigan and Ontario southward; re- 

 ported from several localities in Iowa. 



Extermination. — Prevent from distributing seed by continued 

 cutting before flowering. If it becomes established in a field, try 

 thorough summer fallow with deep cultivation so as to check 

 growth of long rootstocks. 



Fill. 234. 



Blue Lettuce (.Lactuca pulchella). Blue flowered lettuce, 

 milky juice. Common in western Iowa. 

 (Photographed by Quade.) 



Plant with 



