PREFACE. 



Circumstances, over which the Author had no control, have delayed this 

 publication to a most unexpectedly protracted period ; during which the materials, 

 originally extensive, (though chiefly obtained by Dr Richardson, Mr Drummond, 

 and the officers of Sir John Franklin's Expeditions, and by Mr Douglas,) have 

 been so very much increased by the contributions of other travellers, that the 

 two volumes, to which the Author has been limited by his Publishers, have not 

 sufficed to include all the plants of these several valuable collections, nor full 

 generic and specific characters of all such as have been introduced. This being 

 the case, the Author has felt no hesitation in leaving out the whole of the Crypto- 

 gamiay with the exception of the Ferns and allied Orders, and also in omitting, 

 towards the latter part of the work, the definitions of those species which are 

 already well known, or accurately described in the several publications that treat 

 of North American Botany, By adopting this plan, several additional collections, 

 received while this work was in progress,* have been noticed in it, (except, of 

 course, those species which belonged to the early Natural Orders,) and thus the 

 Flora Boreali- Americana will be found to contain a more full and satisfactory 

 account of the Botany of the British Possessions in North America, than could 

 have been anticipated, considering the immense extent of territory here embraced. 



* The Plants here alluded to are chiefly from North-West America, sent by the late Mr 

 Douglas from his last joiimeys, by Mr Tolmie, and by the late Dr Gairdner. 



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