6 
INTRODUCTION. 
Here, the new species of this continent shall 
be chiefly attended to. They are often in as 
great a disorder as the Genera; many are occa- 
sionally blended into one, or improperly deter- 
mined and settled. To give their synonymy is 
not always an easy task, nor are the varieties to 
be overlooked. Many botanists mistake real 
botanical species for varieties or viceversa. In 
fact all species might have been varieties once ? 
and many varieties are gradually becoming spe- 
cies by assuming constant and peculiar charac- 
ters. This is an interesting feature of botanical 
philosophy, which I shall properly explain and 
prove hereafter. 
This new Flora is very far, therefore, from 
being a compilation of former labors : it is quite 
an original work, chiefly based upon my indivi- 
dual researches and discoveries, during 36 years 
of botanical travels and exertions, whereof 24 
were spent in North America, the main field of 
my scientific rambles and labors. 
It may perhaps be useful to give here an out- 
line of my botanical travels in North America, 
whereby it will be perceived that I have survey- 
ed and examined more States and regions than 
any other Botanist perhaps except Nuttall. 
Thus I was enabled to detect a great number of 
New Species, and examine many plants alive in 
full bloom in their native wilds. It would be 
well if botanical writers would thus detail us their 
actual excursions and explorations. 
Some plants are quite local or have very nar- 
row limits of growth, others are only in bloom 
for a few hours or days. Many early vernal 
plants of the Genera Dodecatheon , Clintonia , 
Vernasolis , Viola , Peltandra , Cypripedium , 
can only be seen in narrow localities during 
