The Plants in the red sandstone have been nearly the same from Banbury to Dumfries: the only changes have resulted from difference in elevation, or in the degree of moisture; some changes, but not many, may have been the result of difference in temperature. The plants on the schistus, in the lake district, like those on the calcareous hills of Derbyshire, are much more various than on the sandstone plains; but we have not had leisure to examine the hilly districts with sufficient minuteness to state which plants are peculiar to lime and which to schistus. We suspect, however, that the species limited, or absolute to each will be found very few. Elevation, moisture, and temperature have much more influence on native vegetation than soil. The unity of the flora of the roadsides the whole way from London to Dumfries is beautifully preserved by the bramble and the common polypodiums. These last are very numerous in the neighbourhood of Birmingham, on the coarse sand; and equally so among the lakes between Newby Bridge and Keswick, on the soft compact day. In shady situations, for example, about Levens, near Milnthorpe, and on the east side of Windermere, where the road passes Storr's, the Polypodium vulgare has established itself on the trunks and branches of even healthy vigorous-growing trees, in a manner quite remarkable, and which reminds us of the descriptions given by travellers of the epiphytes in the forests of Demerara and South America. Some sycamores and limes, by the side of the public road at Levens, have their trunks and branches thickly covered with long black moss, in which this fern flourishes most luxuriantly; and a fine oak in the garden of the poet Wordsworth, at Rhydal Mount, is similarly clothed, though not to the same extent. In the drier districts of England this polypodium confines itself to the decaying trunks of old pollards. The wild strawberry is very common on old banks on the sandstone, and also on the clay, and it has grown and spread so vigorously in the neighbourhood of Bowness, and on the banks of the Esk between Longtown and Langholme, as to form on the stone fences strawberry walls, like those of Mr. Byers (Vol. V. p. 437.), in both places. Other walls at Levens, and among the lakes, are completely covered with ferns, which spring from every joint, and from the turf coping. Part of the park fence at Rhydal Hall affords an example.
