PREFACE. 
volume by their introduction. But in order to convey some 
idea of the distribution of plants throughout the United 
Kingdom, the letters E., S., and I. have been appended to 
the descriptions of such species as have, it is believed, been 
found in England, Scotland, or Ireland. The descriptions 
of a considerable number of plants which only occur in the 
Channel Islands, and are, therefore, not properly parts of 
the British Flora, or which, although included in oui- Uste, 
there is reason to suppose have never been really detected 
in Britain, or, although naturalized, have very slender 
claims to be considered as aboriginal natives, are included 
within.[]; and notices of a few plants concerning which 
more accurate information is requisite are distinguished in 
a similar manner. It is hoped that by this arrangement 
the truly indigenous species will be clearly distinguished 
from those which have Uttle or no claim to be considered 
as aboriginal or even thoroughly naturalized. The attempt 
to do this is necessary for two seemingly contradictory 
reasons : namely, the great tendency of many collectors to 
consider as native any plant found growing upon a spot 
where it is not cultivated ; and the peculiar scepticism of. 
some of our botanists concerning the claims of many local 
or thinly scattered species to be admitted as indigenous, 
even when their distribution upon the European continent 
is not unfavourable to the belief that they may inhabit 
Britain. It has been recommended that the descriptions 
of these excluded species should be placed in an Appendix ; 
but as some of them are not imlikely to be observed by col- 
lectors, it is more convenient that they shoiild be arranged 
with their aUies. Those who desire to obtain a complete 
knowledge of the distribution of our plants should consult 
Watson's Cyhele Britannica. 
As in the writings of even the most learned botanists the 
characters of the Natural Orders are far from definite, a 
