DESCRIPTIVE MANUAL 



223 



St. John's-wort (Hypericum perforatum L.). 



Description. — A branched perennial, l%-2 ft. high' with runners; 

 leaves elliptical, or linear-oblong, with pellucid dots; flowers 

 numerous in cymes, petals deep yellow, black-dotted, twice the 

 length of the lanceolate sepals. 



Distribution. — Common in eastern North America in clay soils. 

 Abundant in Iowa only in eastern counties, especially northeast- 

 ward. 



Extermination — This weed spreads both by seeds and by runners. 

 It is difficult to exterminate. Clark and Fletcher give the follow- 

 ing methods: "Close cutting several times during the summer will 

 reduce it in pastures. An application of salt — a small handful to 



Fig. 128. St. John's-wort {Hypericum perforatum). Old fields and woodland 



pastures, eastern and northeastern Iowa. 



(Photographed by Quade. ) 



