rt PREFACE. 



any real difference of opinion as to the richness and diversity 

 of our vegetable productions, hut is occasioned by a different 

 appreciation of the value of the species themselves. The 

 Author has long been persuaded that the views originally enter 

 tained by Linnaeus of what really constitutes a species were 

 far more correct than the more limited sense to which many 

 modern botanists seem inclined to restrict the term ; and that 

 in most cases where that great master had good means of obser- 

 vation, he succeeded admirably in the practical application of 

 his principles. At any rate, if those minute distinctions by 

 which the innumerable varieties of Brambles, of Roses, of 

 Hawkweeds, or of Willows have of late years been characterised, 

 are really more constant and more important than the Author's 

 experience has led him to conclude, they cannot be understood 

 without a more complete acquaintance with trifling, vague, and 

 sometimes theoretical characters than he has himself been able 

 to attain, or than can ever be expected from the mere amateur. 

 It is considered, therefore, that such details would be out of 

 place in the present work, and those who feel sufficient interest 

 in the subject to devote their leisure hours to the investigation, 

 can only hope to master it by a close and patient study of the 

 numerous, often very carefully elaborated monographs published 

 in Germany, Sweden, and France, as well as in this country. 

 The species are here limited according to what are conceived to 

 have been the original principles of Linnaeus, and the Author, 

 in submitting his views to the judgment of the scientific world, 

 trusts that they will not be attributed to hasty generalisations 

 or conjectural theories, but that they will be generally recog- 

 nised as founded on personal observation of living plants, made 

 during many years' residence on the Continent as well as in 

 this country f and on repeated comparison of specimens collected 



' ; leaving 300 to be accounted for by the inclusion of doubtful 

 nd introduced species, and by a subdivision of the bpecies of various 

 mall genera. J. D. H. 



