8 



seeds must have fallen from passing freight cars, and hosts of 

 others might be mentioned. 



Years ago it was a matter of common observation when farm- 

 ers hauled their grain long distances to some market that along 

 the road could be found Chess, Corn, Cockle, etc. It can still 

 be seen but in a less marked degree. 



MIGRATION OF WEEDS. 



Many of our most troublesome weeds are foreigners, as is made 

 apparent from the table at the end of this list. Many have be- 

 come so thoroughly naturalized that it is difficult to make a 

 line of separation of the truly indigenous (native) and those nat- 

 uralized. While we have added a large number of European 

 plants, Europe has received from us, such as the common Horse - 

 weed, Erigeron canadensis, the common Evening Primrose, 

 Oenothera biennis, and Anacliaris canadensis, a harmless North 

 American water plant, said to be so abundant in England 

 as to clog up canals. The number of American plants natural- 

 ized in Europe is, however, small compared with the number of 

 European which have established themselves in this country. It 

 may be due, as some one has suggested, to the greater plasticity 

 of nature in the European flora or power of adapting themselves 

 to circumstances such as our flora does not show. Some of our 

 weeds which were at first ballast plants along the seaports, have 

 moved westward. Prickly Lettuce, Lactuca scariola, which was 

 for many years an adventive in Eastern Few England, has since 

 1874 spread with remarkable rapidity, and is now found in many 

 of the states east of the Mississippi river. Some western native 

 plants have moved eastward and have become pernicious weeds. 

 Solanum rostratum. a native of Kansas and Southwest, has traveled 

 eastward and has been reported from New York. Of the less 

 troublesome weeds Worm Wood, Artemisia biennis, Cone Flower, 

 Fudbeclia hirta, are reported as common in the East and inclined 

 to be " weedy." 



In the arrangement of the orders and genera I have followed 

 Bentham & Hooker's Genera Plantar urn. The nomenclature is 

 that given in Dr. Gray's Synoptical Flora of North America 

 (Gamopetalae), Watson's Bibliographical Index to North Ameri- 

 can Botany (Pt. 1 Polypetalae), Botanical contributions by 

 Sereno Watson and Dr. Gray and Vasey Grasses of the United 

 States. 



The introduced weeds are printed in Italics. 



