WEED MIGRATION 



709 



Fig. 543. Jimson Weed (Datura stramonium). An immigrant from India, 



reached United States by way of Europe. 



(After Chesnut, U. S. Dept. of Agr.) 



1814, records 83 introduced species and in the edition of 1840, lists 

 140 species. Dr. Fernald says : ' ' Gradually this list has increased 

 until we are forced to number among the wild plants of New 

 England more than 600 species which have been introduced through 

 human agency since the first cutting of the forests." The causes 

 for the appearance of these weeds into New England, the west, 

 Pacific coast and elsewhere must be ascribed to the sowing of 

 seed that contained the weed seeds. Wheat always contained the 

 seed of cockle, mustard, vetch, etc., consequently we find that 

 these weeds are found wherever cereals are cultivated. Many 

 plants were, however, planted for medicinal purposes, among 

 which were peppermint, black henbane, tansy, chamomile, caraway, 

 poison hemlock, and a long list of other plants utilized by the Mor- 

 mons which have become weedy wherever these people have settled. 

 Even in Iowa we find that such plants as tansy, elecampane, jimson 



