WEED MIGRATION 



705 



Fig. 541A Fig. 541B 



Fig. 541. A and B. Small Ragweed (Ambrosia artemisiaefolia) . An immigrant 



from the southern part of the United States. 



(Vasey, U. S. Dept. of Agr.) 



carolinense, various species of Amarantus and Euphorbia, Panicum 

 capillar e, etc. Of late, and in consequence of increased communi- 

 cation with the Mississippi region and beyond — especially by rail- 

 roads — other plants are coming into the eastern states as weeds, 

 step by step, by somewhat rapid strides ; such as Dysodia chrysan- 

 themoides, Matricaria discoidea, and Artemisia biennis. Fifty 

 years ago Rudbeckia hirta, which flourished from the Alleghanies 

 westward, was unknown farther east. Now, in twenty years, it has 

 become an abundant and conspicuous weed in grass fields through- 

 out the eastern states, having been accidentally disseminated with 

 red clover seed from the western states. 



There are also native American weeds, doubtless indigenous to 

 the region, such as Asclepias cornuti, Antennaria niargaritacea and 

 A. plantagini folia, and in enriched soils Phytolacca decandra, which 

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