Plants growing on their superincumbent Soils. 417 



Er^dium cicutarium, or moschatum, belongs, I am inclined 

 to believe, to the new red sandstone. The sand-hills of Bootle 

 and Southport are covered with it, and considerable quantities 

 appear on the banks of the Irwell at Barton. 



The slate and transition limestone districts claim Convolvu- 

 lus Soldanella. The only localities I ever found of this plant 

 are, the mouths of the river Conway, and of the Ex in De- 

 vonshire. 



The heaths are found most luxuriant where granite or other 

 primitive rocks are found. * These plants, as their names im- 

 ply, are found always on bog soil ; and, as the component 

 particles of that earth may be taken as similar every where, 

 yet it cannot be denied that the heaths of different contiguous 

 hills are extremely different both in kind and degree. Red 

 heather (Erica cinerea) is the only species found for miles 

 together on the greywacke of the Isle of Man ; E, Tetralix, the 

 only species for several hundred yards on Blackstone Edge ; 

 E. vulgaris is the only species for miles on the granite of 

 Goatfell, in the Isle of Arran. Each of these species may be 

 found in sufficient quantity wherever bog soil is found ; but 

 they may reasonably be claimed by those districts only, where, 

 with equal climates, they are produced in greatest luxuriance : 

 and few observers of the common features of a landscape can 

 have failed to notice the great diversity of character in these 

 universal natives of our moors, in the different geological 

 arrangements of the country. Few can have omitted to notice 

 the total want of them on bog whose substratum is chalk or 

 mountain lime ; and many have been delighted with their 

 abundance and surpassing beauty in the primitive ranges of 

 Wales and Scotland. The ling of Pont Aber Glas Llyn, 

 near Reddgelert, yields to none in the richness of its flowers ; 

 and that of the granite range of Avan, in the Frith of Clyde, 

 is often 3^ ft. in height, arborescent, and erect, like the finest 

 specimens of Cape heaths cultivated in our green-houses. 

 The poor natives of that island make an economical substitute 

 for hemp from its twigs ; and the roots, occasionally thrown 

 out of the soil by the fury of a mountain-torrent, are 2 in. in 

 thickness, and capable of a high polish, being nearly as hard 

 as ebony. The Cape of Good Hope itself, which has supplied 

 our exotic collections with nearly 300 species of this genus, is 

 one of the finest granite ranges in the world. 



Several species of Trifolium are found in a singular manner 



* Were it possible to conceive the universality of a vegetable soil, what 

 would be the effect ? I presume, a decrease of vegetation in general, and a 

 total extinction of those plants best fitted to support animal life ; the whole 

 of which, nearly, arc the productions of rock soil. 



