WITH LATITUDE AND LONGITUDE. 83 



physical features in every other respect, how greatly 

 would the vegetation become changed ! 



Latitude, longitude, altitude, and minor conditions, are 

 so inseparably united in their influence over vegetation, 

 that one cannot be considered apart from the others, with 

 any reference to dependence or causation. The regions, 

 already pointed out, relate to the distribution of plants 

 under these combined influences. The mere range of 

 latitude for each species is attempted to be shown in the 

 Appendix Table by naming the most southern and most 

 northern degree under which I am aware of a station on 

 tolerably good authority, and without any very strong 

 reason for suspecting error. Several will probably be 

 found to extend beyond the latitudes named for them, 

 especially towards the extremities of the island ; and in 

 Scotland more than in England, in consequence of local 

 botany being less attended to in the former country. It 

 was wished to distinguish the ranges of latitude, in which 

 species are indigenous, from those to which they have 

 been introduced ; but, after much labour, it was found 

 necessary to abandon the attempt at present. The eager 

 desire manifested by botanical collectors to call their 

 specimens " truly indigenous," however small the evi- 

 dence thereof, raises insurmountable obstacles. 



The above-mentioned Table does not include the 

 longitudinal range. On account of the narrowness of 

 Britain, its oblique position with reference to the poles of 

 the earth, and the deeply indented coasts, no single 

 meridian line divides the eastern from the western coasts ; 

 and in no other respect does the distribution of our plants 

 appear to have any necessary connection with longitude, 

 than as regards their tendency to the eastern or the 

 western coasts. The mesial line of England and Wales, 

 apart from Scotland, closely corresponds with 2° W. long, 

 from Greenwich, and entirely divides the eastern from 

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