iv 
PREFACE. 
convinced the Author that they are reijuired. He may have 
fallen into error, but has earnestly endeavoured to discover 
the truth. 
Attempts have been made greatly to reduce the number of 
recognised species found in Britain ; but the results obtained 
seem to be so totally opposed to the teaching of the plants 
themselves, and the evidence adduced in their favour is so 
seldom more than a statement of opinion, that they cannot 
safely be adopted ; nor does the plan of the present work 
admit of a discussion of the many questions raised by tliem. 
Also it has been laid down as a rule by some botanists, that 
no plant can be a species whose distinctive characters are not 
as manifest in an herbarium as when it is alive. We are told 
that our business as descriptive botanists is not " to determine 
what is a species," but simply to describe plants so that they 
may be easily recognised from the dry specimen. The Author 
cannot agree to this rule. Although he, in common with 
other naturalists, is unable to define what is a species, he 
believes that species exist, and that they may often be easily 
distinguished amongst living ])lants, although sometimes' 
separated with difficulty when dried specimens alone are 
examined. He thinks that it is our duty as botanists to study 
the living plants whenever it is possible to do so, and to 
describe from them ; to write for the use and instruction of 
field- rather than cabinet-naturalists ; for the advancement 
of a knowledge of the plants rather than for the convenience 
of possessors of herbaria : also that the differences which we 
are able to describe as distinguishing plants being taken from 
their more minute organs, does not invalidate their claim to 
distinction. It seems to be our business to decide upon the 
probable distinctness of plants before we attempt to define 
them — to make the species afibrd the cliaracter, not the 
character define the species. 
Tliis volume being intended as a field-book or travelling 
