x PREFACE. 
Linnzus, considering only the external appearance of 
the flower and fruit, despaired of finding this clue; but the 
favourers of the older arrangements have bestowed so much 
attention in examining the internal organization of plants, 
particularly of the fruit and seed, and various organs, which 
were neglected by the Linnean nomenclators, that this 
-desirable point is now attained. The present work exhibits 
the results of the latest investigations into the mutual 
affinities of plants; and the synopsis of the subdivisions 
attached to the several divisions furnishes a clue which will 
enable a student to trace the connexion of the several parts, 
and their dependence upon each other. When the author 
considered the great pains which had been taken with many 
of the families, and especially with those, which, from their 
not plainly exhibiting the sexual organs, were huddled 
together by Linnzeus in his twenty-fourth class, which 
contains probably far more plants than all his other 
twenty-three classes put together; and that there had not 
yet appeared in this country any detailed account of these 
researches, he was led to engage in preparing this system 
for the use of the English students of this delightful species 
of knowledge. 
An essential difference exists between the mere deter- 
mination of the name of plants, and the study of their 
affinities to each other. ‘The nomenclature of plants re- 
quires the study of so many only of their organs, and such 
a slight consideration of these as may suffice to determine 
the difference that may exist betwixt any two plants that 
might otherwise be confounded. The scientific study of 
their affinities requires, on the contrary, the whole of their 
organization to be kept in view, and the changes it may 
undergo during their natural life; hence there arises a 
necessity for a more accurate discrimination of the various 
forms of their organs than is required for the nomenclature 
only. The botanists of the natural school have, therefore, 
been led to invent a far greater number of terms than were 
introduced into use when Linneeus wrote his Philosophia 
