BOTANICAL GEOGRAPHY. 
31 
Why have we so few Crucifera, Umbellifera 
and Narcissides, compared to Europe and Af- 
rica ? 
Why are the two shores of North America, 
east and west, so unlike to each other in vege- 
tation ? 
These queries and others of a similar nature 
may exercise the ingenuity of speculative Bo- 
tanists, or amuse their idle hours; but they are 
facts and as such deserve our notice. 
Another interesting study is that of our na- 
turalized plants. We have so many that they 
appear to invade the fields and drive out the na- 
tive plants in some instances ; but it is by no 
means certain but that some deemed natura- 
lized, were not really native. Such at least 
must have been the case with Verbascum thap - 
sus , Hypericum perforatum , Daucus carota , 
Anthemis cotula , Origanum vulgar e^ &c. 1 
gave a long list of the naturalized plants in my 
dissertation of 1808, some have since disappear- 
ed, while others have appeared instead out of 
gardens. But few American plants have be- 
come spontaneous in Europe, Phytolaca decan- 
dra and Cenotis canadensis are mentioned as 
such ; but we have received several hundreds, 
besides some few from the Antilles and inland 
Decandole has properly stated that naturalized 
plants even when not spontaneous, but exten- 
sively cultivated in the open air ought to be ad- 
ded to every general flora, and Eaton has fol- 
lowed that advice with us. 
It appears that even previous to the discovery 
of America by Columbus, our Indian tribes had 
received or imported from abroad or the South, 
several trees and plants. I have at least evi- 
dently ascertained historically that this was 
