Page:Transactions of the Natural History Society of Northumberland, Durham, and Newcastle-upon-Tyne (1867).djvu/60

44 The Xerophilous species adapt themselves to the basalt and porphyry to some extent, more so than to any other kind of rock except limestone, a circumstance which would lead one to suppose that it is the mechanical, rather than the chemical constitution of the rock, that is influential in attracting them. Besides the four species marked with a star in the preceding list, five others, ,, , , and , have a fair claim to be regarded as Cheviot plants; and the same is true, even to a still greater extent, with the basalt. The Cheviot heights are much less heathery and more grassy than the sand-stone moors, but they are almost as monotonous from the botanical point of view, and totally destitute, still speaking botanically, of any characteristic features. Take Cheviot itself for an example. Although the hill rises very nearly to 900 yards, and there is a wide extent of surface above 650 yards, we believe the following to be very nearly a complete list of the plants which exceed the latter altitude.