212 Postelsia 
unknown. In the light of further knowledge 
of these forms, it has been necessary to greatly 
modify the original definition of the groups, 
while the distinctions between them have be- 
come much more vague and indefinite than 
they were formerly supposed to be. 
In the light of these facts, it has seemed 
best to give Abies its wide significance, rec- 
ognising as sections of this genus several groups 
of plants which are currently considered genera. 
Larix, Pseudolarix and possibly Cedrus also, 
are regarded as small genera very closely allied 
to Abies, but differing from it in a somewhat 
more marked manner than the sections of Abzes 
differ from one another, while Pinus is a second 
large and complicated genus clearly distinct 
from Abies. 
