Rocks with Planis. 341 



to that of Edinburgh than to the Devonshire flora : and this is 

 a circumstance of great importance, in relation to. the present 

 object, when we consider it in connection with the fact, that, 

 so far as rocks are concerned, this county is totally unlike to 

 the tract around Edinburgh ; whereas it is by no means equally 

 dissimilar to Devonshire, which contains a considerable, por- 

 tion of granite, our prevailing rock. 



Enough has, I hope, been said to show that the opinion of 

 those who believe the native vegetation to be defined by the 

 rocks is not supported by a priori reasoning or by facts. 

 This view of the matter was derived entirely from my own 

 consideration of the subject ; but I am glad that it accords 

 exactly with the opinion of the Rev. J. P. Jones and J. F. 

 Kingston, whose excellent observations I may quote, as they 

 admirably confirm my views : — " With all this variety in the 

 rock strata (of Devonshire), we know of no peculiar vegetable 

 features by which to distinguish one formation from another. 

 The Cistineae, Conyza squarrdsa, and one or two other plants, 

 seem to affect the limestone ; the Clematis also appears to 

 grow more luxuriantly amongst the crevices of that rock 

 than elsewhere ; whilst the /Vis fcetidissima and the elm 

 prevail most in red sandstone : still, neither of them, nor any 

 other species, so far as we are aware, is exclusively con- 

 fined to any particular formation. We may trace the same 

 plants frequently along the whole of our coast line, whether 

 the cliffs are sandstone, limestone, or slate ; and, if we choose 

 to push our investigation farther along those of Cornwall, we 

 may still find them in the serpentine formation of the Lizard 

 district, and in the granite rocks around the Land's End." 



It is probable that the distribution of vegetables is mainly 

 regulated by climate : a term implying a combination of cir- 

 cumstances, which depend very much upon altitude and lati- 

 tude.* I presume it would be found that, in general, dif- 

 ferent floras resemble, or differ from, one another, not with 

 any regard to the rocks, but according as the regions to 

 which they relate are similar or not in altitude and latitude. 

 The same leading rocks, and these but few in number, every 

 where occupy the greater part of the earth's surface ; yet, in 

 some climates, how different is the vegetation from that which 

 is found in others ! Though the rocks are essentially similar, 

 the vegetation of the mountainous part of Aberdeenshire is 



* The researches of Hewett Cottrell Watson, Esq., on the geographi- 

 cal distribution of British plants, have a relevant relation to this second 

 question ; as shown in his Outlines, and in his communications to some 

 recent numbers of Jameson's Journal. A notice of the Outlines has been 

 given in p. 265-7. of the current volume of this Magazine. — J. D. 



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