Geographical Botany of the United States. 21 



racy necessary to a full developement of this subject. But as far 

 as can be judged from the materials which we possess, the same 

 remarks will apply. It has already been stated, that in South 

 Carolina and Georgia, various species of Pine, which in this lati- 

 tude are found on the low lands, are there confined to the summits 

 of the mountains. Drs. Bigelow and Boot, found on the summit 

 of the White Hills, in lat 44° 15' N. at 6000 feet above the 

 level of the sea, natives of Lapland, Greenland and Labrador; as 

 Epilobium alpinum, L. Empetrum nigrum, L. Ledum latifolium, 

 Ait. Menziesia car idea, Swartz, Ruhus saxatilis, L. Diapensia, 

 Lapponica, fyc. So also those who crossed the Rocky Mountains, 

 witnessed the same changes of vegetation. 



The botanical examination of high mountainous tracts, whether 



est; as it affords, within a small compass, striking illustrations of 

 many leading facts in geographical botany. At the base, vegeta- 

 tion is thrifty, the species are numerous and similar to those of sur- 

 rounding regions — Upon ascending, these forms become stinted in 

 their growth, and gradually disappear. Others succeed, still more 

 dwarfish and hardy, and in their turn give place to the few repre- 

 sentatives of the polar regions, which continue to the limit of eter- 

 nal snow. In such a journey, therefore, the traveller passes as it 

 were, in quick succession, from the equator to the poles. 



A great peculiarity in the vegetation of the United States, and 

 which strikes the traveller as well as the botanist, is the number 

 and variety of its Forest Trees. This will be fully exhibited when 

 we remark, that the single genus of Oak, comprehends within the 

 United States, more species than Europe reckons within the whole 

 amount of its trees. But this subject, together with a notice of 

 the distribution of the Grasses, and other families of plants, will be 

 noticed more in detail hereafter. 



