110 ROCK PLANTS OF THE PASTURES 



only one species, which has, however, a wide 

 distribution. 



In Alpine Switzerland the Trailing Azalea is fairly 

 common in all sorts of habitats. It may occur in 

 woods which are not very dense (p. 248), on flat- 

 topped hills resembling moorlands, and elsewhere, 

 though it generally inhabits some slab of rock or 

 some patch of dry stony ground. It occurs in the 

 Highlands of Scotland, where it also forms a carpet 

 on the flat dry hilltops. When grown in the Low- 

 lands, it may abandon its prostrate, trailing habit and 

 become erect. 



The small leaves of this plant are worth examining. 

 It will be found that they are rolled inwards at the 

 edges. The stomata or pores are situated on the 

 lower surface in two grooves near the edges, which 

 are filled with hairs and further protected by the 

 incurving of the leaf at the margins. Similar adapta- 

 tions to guard against excessive loss of moisture from 

 the leaf are found in the leaves of the Alpine Heath 

 {Erica carnea), the Ling {Calluna vulgaris), and the 

 Black Empetrum {Empetrum nigrum). 



The Alpine Globularias. 



In the Alpine Globularias, of which there are two 

 species — the Round-leaved Globularia {G. cordifolia, 

 Linn.) and the Bare-stemmed Globularia {G. nudi- 

 caulis, Linn., natural order Sekginese, the Selago 

 family) — we have a family of plants which does not 



