ORIGIX OF WEEDS 453 



carrot, wild parsnip, tansy, oxeye daisy, and field garlic are 

 instances of this. 



430. Origin of weeds. 1 By far the larger proportion of our 

 weeds are not native to this country. Some have been brought 

 from South America and from Asia, but most of the introduced 

 kinds come from Europe. The importation of various kinds of 

 grain and of garden seeds, mixed with seeds of European weeds, 

 will account for the presence of many of the latter among us. 

 Others have been brought over in the ballast of vessels. Once 

 landed, European weeds have succeeded in establishing them- 

 selves in so many cases, because they were superior in vitality 

 and in their power of reproduction to our native plants. This 

 may not improbably be due to the fact that the European and 

 western Asiatic vegetation, much of it consisting from very early 

 times of plants growing in comparatively treeless plains, has for 

 ages been habituated to nourish in cultivated ground and to 

 contend with the crops which are tilled there. 



1 See the article, " Pertinacity and Predominance of Weeds," in Scientific 

 Papers of Asa Gray, selected by C. S. Sargent, Vol. II, pp. 234-242. 



