raclcuin, and CEnanfhc. It will be seen that nearly half of ou r 

 genera arc represented by single species. 



The following tabic shows the general distribution of our 

 genera. The first column gives the whole number of species 

 found in North America north of Mexico; the second, the number 

 of introduced species; the third, those species that are strictly east- 

 ern, incliuling a single tier of states west of the Mississippi; the 

 fourth, those species that are western, that is, from the plains 

 westward; the fifth, those that are found both east and west, some 

 of which ma\ be of wide range, and others southwestern and so 

 overlapping the boundary between the two regions; the sixth, 

 the number of species accredited to each genus throughout the 

 world, as indicated by Bentham & Hooker, somewhat modified by 

 the more recent changes. The genera marked with an asterisk 

 (*) are endemic. 



