FLORA OF THE WEST YORKSHIRE HILLS. 263 



and ling, sundew, the purple Molinia, mat-grass, rushes, sedges, 

 bog-moss, bilberry, and, high up above all, the cloudberry, a 

 relation of the common bramble. The yellow-flowered Bog 

 St. John's Wort {Hypericum elodes), however, is an exception to 

 this rule. It can, and does, grow on a peaty soil. In sandy soils 

 such plants as broom, hawkweed, sheep's sorrel, woodsage, fox- 

 glove, and birdsfoot trefoil abound, though they are not absolutely 

 confined to such situations. On limestone, the heathers and 

 bilberry, so common on a peaty soil, and foxglove so abundant on 

 a sandy soil, are altogether absent, and the hairy violet, rockcress, 

 and salad burnet are the characteristic plants. Clayey soils are 

 distinguished by an abundance of white clover, sneezewort, colts- 

 foot, and fleabane, though these again are not absolutely peculiar 

 to such soils. 



In no case, however, does elevation exert its influence alone. 

 It must always be considered in connection with, and in relation 

 to, the degree of moisture, and the kind of soil. For instance, as 

 we shall see hereafter, certain plants will grow higher up the slopes 

 of limestone hills, which are as dry and warm as any in the 

 county, in greater luxuriance than they will on damper hills of 

 some other formation ; and other plants will descend to lower 

 levels, when they can find the moisture in the presence of which 

 they are accustomed to grow. 



The hills which extend along the Western borders of York- 

 shire may be divided into two sections — a northern and a southern, 

 each of which is marked by a characteristic geological formation. 

 In the Northern section are numerous lofty and steep ledges of 

 limestone rock approached by shelving slopes, covered with short, 

 bright green, thin but nutritious grass. To the eye of a spectator 

 suitably situated for observation, the prevailing tint of this region 

 would be green, with here and there darker patches, the latter 

 indicating the places where the limestone is overlaid by the mill- 

 stone grit. Unlike the limestone, the millstone grit is devoid of 

 the conspicuous grassy covering and is overspread with stretches 

 of heather and peat. These last it is which impart the sombre 

 touches to the otherwise bright landscapes. The whole of the 

 southern section is capped by the millstone grit, and here its con- 

 comitant crown of dark, wild, and dreary peaty moorland is 

 universal. 



