384 



WEED FLORA OF IOWA 



Fig. 224-A. Distribution of Knapweed. 



Distribution. — ^Massachusetts to Ontario and Iowa; introduced 

 with alfalfa seed into other western states. 



Extermination.— This annual weed has been introduced largely 

 with alfalfa seed. Sow clean seed. Use seed coming from the 

 Rocky mountains or Kansas where the weed is not common. It is 

 an extremely objectionable weed because of the spiny heads. It 

 is easily killed by- cultivation. 



CJiicpry or Succory {Cichorium intyJnCs It:). 



Description.^— A branching perenjiial with deep roots, alternate 

 leaves; blue flowers, or sometimes pink or purple; basal leaves 

 spreading on the ground; stem leaves oblong or lanceolate, 

 partly clasping. 



Distribution.— It is common alonfe roadsides in fields and waste 

 places from N^w England to Canada to Nebraska, especially com- 

 mon where chicory has been cultivated; it has become a trouble- 

 some weed in Wisconsin and Minnesota. It is allied to endive, cul- 

 tivated as a salad plant. 



Extermination. — Chicory is not difficult to destroy where ro- 

 tation of crops is practiced. Though a perennial, the roots are 

 easily killed by repeated cultivation. 



Clark and Fletcher recommend the following treatment: 

 "A short rotation of crops will soon suppress it. Chicory is not 

 often seen in good farming districts except as a wayside weed. 

 Individual plants may be destroyed by close cutting and applying 

 salt to the root in hot, dry weather." 



