INTRODUCTORY EXPLANATIONS. 
The Supplement to the “ Flora of Yorkshire ” contains a complete list 
of the flowering plants, ferns, and mosses, known or reported to grow 
wild within the limits of the county, so far as they hare been ascertained 
by those who have contributed towards it, at the close of the year 1853. 
Since the original “ Flora ” was published, fourteen years have elapsed. 
During the interval much has been accomplished in collecting facts and 
details relative to the geography of the plants of Britain, and connecting 
together the records of their localities and situations which have been 
gradually accumulated. By arranging and comparing these, considerable 
progress has been made in tracing the leading features of the distribution 
of the species which compose the (phanerogamic) flora of Britain over 
the surface of the island, and investigating the laws and conditions which 
govern and limit their diffusion. The era of the “ New Botanist’s Guide” 
has passed away, and is succeeded by that of the “ Cybele Britannica.” 
During the interval, also, Babington’s “ Manual of British Botany” has 
replaced Hooker’s “ British Flora,” as a popular descriptive handbook and 
standard of nomenclature. The most characteristic feature of this work, 
which has already, passed through three editions, is an endeavour to 
establish uniformity in the nomenclature employed in this country, with 
that of the most trustworthy continental authorities of modern times, 
amongst whom Koch and Fries are pre-eminent. In order to attain this, 
numerous alterations from the names previously adopted have been 
rendered necessary. Many species before unknown within the limits of 
Britain have been found, upon closer examination, to extend their range 
to this country. And others, which were formerly supposed to be single 
species only, are found, upon more accurate investigation, to require sub- 
division. So that the fourth edition of the “ London Catalogue of British 
Plants ” is very different from what any similar enumeration which might 
have been attempted in 1840 would have been. 
