154 Plants of Europe naturalized in the Ufiited States. 



124 Periploca grceca. New York. , 



125 Chenopodium bonus henricus. 



126 Hemerocallis fulva. 



127 Tanacetum vulgare. 



12S Achilicea ageratum. North Carolina, in some localities. 



129 Tussilago farfara. Pennsylvania. 



130 Helianthus tuberosus. Pennsylvania and Carolina. 



131 Centaurea cyanea. 

 132 nigra. 



1 33 jacea. 



134 henedicta. 



135 calcitrapa. 



136 Prunus spinosa. New England. 



137 Dipsacus sylvestris. Pennsylvania. 



No Scabiosa, no Viola, no Papaver, and no other segetal plants 

 occur at all naturalized. The Bellis perennis, so universally 

 disseminated in Europe, is never seen. None of the shrubs 

 usual in hedge-rows, have become naturalized. It is particu- 

 larly remarkable, that the Centaurea cyanea, though very fre- 

 quently cultivated for ornament, in the gardens of the German 

 farmers in Pennsylvania, has never spread into grain fields, in 

 which it is so prevalent in Europe. This is likewise the case 

 with Delphinium consolida and many others ; while the intro- 

 duction into a garden in North Carolina oi Antirrhinum linaria, 

 and of Stella7-ia media, in a very few years contaminated the 

 whole vicinity for many miles. The readiness with which 

 plants like Leontodoti taraxacum, Cfiicus lanceolatus, &c. 

 with feathered seeds spread, is easily conceived. Not so 

 readily explained is the cause which renders Anthemis cotula 

 so wonderfully prevalent. In the mean time it is observable 

 that a large river is apt, as well as a tract of land intervening 

 entirely unsuited to the growth of some of these emigrants, to 

 stop their progress for a time. But when once the passage is 

 forced at any point, the dissemination appears to proceed the 

 more rapidly. 



In 1823, the Anthemis arvensis, or cotula, in Tuscarawas 

 county, Ohio, had widely spread up to the eastern bank of the 



