262 



WEED FLORA OF IOWA 



Fig. 211-A. Distribution of Mayweed. 



Ox-eye Daisy (Chrysanthemum leucanthemum L. var. pinnatifidum 



(Lecoq) Lamotte). 



Description. — A perennial herb with erect stem; spatulate, peti- 

 oled, root leaves, those of the stem partially clasping, all leaves 

 cut or pinnatind-toothed ; nearly simple stem bearing a large, 

 many-flowered head with numerous white rays; scales of involucre 

 with scarious margins, both disk and ray flowers producing 

 achenes, marked with longitudinal lines; pappus absent. 



Distribution. — This European weed has long been known as a 

 troublesome weed in New England and the central states. It is 

 not abundant in Iowa except in a few places. 



Extermination. — This weed is not troublesome as yet in Iowa. 

 There is much danger, however, that it may be introduced with 

 clover seed, as it frequently occurs in eastern and European 

 grown clover seed. Sow only clean clover seed. It succumbs quite 

 readily to cultivation. 



Clark and Fletcher make the following recommendations : ' ' Shal- 

 low plowing of sod in August, with thorough cultivation from time 

 to time until frost, will suppress it. This pest does not give trouble 

 on lands worked "under a short rotation of crops. Clover for hay 

 in which this weed is plentiful should be cut early. ' ' 



