PREFACE. 
vii 
less degree, Lloyd's Flore de VOuest de la Frattce, Brebisson's 
Flore de la Normandie, and Cosson and Germain's Flore des 
environs de Pai'is, ed. 2. Boreau's Flore du Centre de la 
France, ed. 3, and the scattered papers of M. Alexis Jordan 
of Lyons are valuable for the study of varieties ; for many of 
their species can claim no higher rank. But, above all, the 
woi'ks of Fries deserve careful study —especially his Xovitive 
Florae Suecicce, with its three Mantissce, and Summa Vegetah- 
ilium Scandinavice. It is necessary to warn students against 
the very common error of supposing that they have found one 
of the plants described in a foreign Flora when in reality they 
have only gathered a variety of some well-known British 
plant. The risk of falling into'such errors renders it necessary 
to consult such works as those of Messrs Boreau and Jordan 
with great caution, lest we should be misled by descriptions, 
most accurate, indeed, but often rather those of individuals 
than species. Amongst plants so closely allied as are many 
of those called species in some continental works, it is 
scarcely possible to arrive at a certain conclusion without 
the inspection of authentic specimens. 
The Author takes this opportunity of returning most 
sincere thanks to his botanical friends and correspondents 
(far too numerous to record by name) for the great assistance 
they have again rendered to him by the communication of 
valuable suggestions, observations, and specimens. 
The book has been again carefully revised throughout, 
so as, if possible, to keep pace with the rapidly advancing 
knowledge of British plants. 
As many as possible of the real English names are given. 
All the genera and species could not be thus named, owing 
to the absence of any recognised English terms which have 
been applied to them. It does not seem desirable to invent 
or adopt new English names, known only to botanists, for 
the few genera which have them not, the Latin name being 
