PREFACE. 
Vll 
botanical region. With the exception of the small patches of 
alpine vegetation which crown the higher mountains of Northern 
New England and Northern New York ; of the sea-side plants, 
and of some appropriately Southern forms which not only reach 
Delaware and New Jersey (especially the Pine barrens), but also 
straggle northward coastwise, in diminishing numbers, quite to 
New Hampshire ; of a very few which belong to the Great Lakes; 
and perhaps a larger number of Western prairie plants which ex¬ 
tend into Ohio, Wisconsin, and Michigan,—with these excep¬ 
tions, the vegetation is remarkably homogeneous for so large a dis¬ 
trict, and a very great proportion of the species are sporadic over 
the whole breadth. The peculiar plants, though few as to num¬ 
ber of species, suffice to give a marked character to the confines 
on either side, which, however, soon blends insensibly into the gen¬ 
eral mass as we advance into the interior. Although I do not for¬ 
mally include Indiana, yet its botany apparently belongs quite as 
much to our Northern district as to the Western, that of the 
Upper Mississippi, to which Illinois clearly belongs. Those spe¬ 
cies for which no particular limit or geographical range is indicat¬ 
ed may be expected to occur, at the stations they severally affect, 
throughout the whole district. By appending the words south¬ 
ward ,, northward , &c., I endeavour briefly to indicate, in a manner 
sufficiently precise for the purpose, the part of the country where 
a given species prevails, or the direction from which it may be 
supposed to have reached our district. 
The more striking and distinctive points of the ordinal character 
are brought together and printed in italics in the first sentence of 
the description of each order, so that they may the more readily 
strike the student’s attention. To abridge the labor of analysis 
as much as possible, I have given an easy synopsis of the genera 
under each order, whenever it comprises three or more of them ; 
