2 MONOGRAPH OF THE GENUS ALLIUM, 
the difficulty of determining the species already dscribed, 
and the general intricacy of the whole genus ; for, although 
many of the species afford good and permanent marks of 
distinction, it must be admitted the limits of others are not 
so easily determined. 
Although the genus Allium is very extensive, I have 
thought it best to retain it entire, considering it truly na^ 
tural. In order to facilitate the arrangement of the species^ 
I have divided the genus into divisions and sections, which 
are severally characterised in their proper places. Some 
authors have regarded several of these divisions as sufficient 
to constitute distinct genera. 
The Alha are exclusively confined to the temperate 
zones, with the exception of a very few species, which are 
found in elevated regions within the tropics; and the 
greatest proportion of them are found in Europe, and the 
Asiatic provinces of the Russian empire. 
In Allium, the flowers are disposed either in an umbel 
or a globular head, and the pedicels issue from a common 
centre ; while in the neighbouring genera, Ornithogalum 
and Scilla, they are always corymbose, with pedicels arising 
alternately from the sides of the rachis, which as they ad- 
vance elongate into racemes. 
In regard to the synonyma, I have been as careful as 
my opportunities would admit ; and I trust I will be fo\md 
in many instances to have satisfactorily cleared them up. 
Much still remains to be done in this intricate genus, 
notwithstanding the labours of Halle r and Dr Trevi- 
RANUS, and I am far from supposing the present essay 
complete. My object will be attained, if I have been so 
fortunate as to lessen the difficulty attending the study of 
this genus. It is only by degress we can arrive at per- 
fection. 
