OF NORTH AMERICA. 5 



Tne woody structure and permanence over 

 ground during Winter under a state of hyber- 

 nation, with evergreen leaves or sleeping buds, 

 might most properly distinguish this series of 

 Vegetation, and XYLOGY might be a better term 

 to apply collectively to their knowledge than 

 Dendrology and Thamnology. 



Every one of the Botanical Regions of North 

 America is distinguished by peculiar Trees, 

 Shrubs and Vines ; in fact they form the most 

 prominent feature of each by their size and per- 

 manence. See my botanical regions. 



Although so much attention appeared to be 

 paid to these ornamental and useful produc- 

 tions, it was only lately that the multitude of 

 our Pines, Oaks, Willows, Poplars, Ash trees, 

 Hicories, Vines, Roses &c have been ascer- 

 tained : and it is a fact that many Genera are 

 as yet little attended to or in utter confusion; 

 many species and varieties being overlooked or 

 blended as were formerly those of Oaks, Ash 

 trees before Bosc &c: my own sp. of Rosa and 

 Vitis, well distinguished by me, are neverthe- 

 less invisible to some blind Botanists around 

 me. I have been engaged for years in study- 

 ing the fine Genus Prunus, now divided into 

 Prunus, Cerasus, Padus, Orospodias &c, 

 and instead of 20 I know 30 or 40 species of it. 

 I have discovered and possess a crowd of N. 

 sp. belonging to the Genera Prinos, Hex, Spi- 

 rea, Ceanothus, Rhamnus, Celtis, Pavia, 

 Hydrangea, Viburnum, Caprifolium, Evo- 

 nymus, Clematis &c. I have even some new 

 Genera of shrubs to describe in this Sylva. 



The Genera Vaccinium and Andromeda, 

 must be divided into many, and quite reformed, 

 revised, corrected as to sections and species. 



