WEED MIGRATION 



713 



New introductions have come not only into western Europe 

 from the United States, but from eastern Europe, Asia, and from 

 the tropical world. The Berteroa incana, a recent introduction 

 into Iowa, has been reported in Germany by Scherer. The spiny 

 knapweed {Centaur ea solstitial^) , a recent Iowa introduction, has 

 been reported from Germany by Lehmann, Bitter and Alpers. The 

 Galinsoga parviflora, an introduction from South America into 

 the United States, has been reported from northern France and 

 southern Germany by Kieffer. The storksbill {ErocHum mos- 

 chatum), the butterprint {Ahutilmi theaphrasti) , the spiny clotbur 

 {XantMum spinasum) and the shoo-fly {Hibiscus trionum), are 

 common plants of the tropical regions everywhere; these have ex- 

 tended far northward. In recent years they have been reported in 

 north Germany by Bitter. He has likewise reported as recent in- 

 troductions the yellow sweet clover {Melilotus officinalis), Matri- 



FiG. 547. Velvet Weed or Butterprint (.Adutilon theophrasti) . A tropical weed 



now common in the north and spreading to Europe. 



(U. S. Dept. of Agr.) 



