68 DISTRIBUTION OF PLANTS 



We have in consequence a much more ample catalogue 

 of species for the Scottish subalpine region. Directing 

 attention chiefly to the open declivities and summits, we 

 first see Gnaphalium supinum, Carex rigida, Cerastium 

 alpinum. Above these occur Azalea procumbens, Silene 

 acaulis, Juncus castaneus. Then succeed Hieracium al- 

 pinum, Juncus trifidus, Salix herbacea, Sibbaldia pro- 

 cumbens. Still higher appear Cherleria sedoides, Juncus 

 biglumis, Cerastium latifolium, Veronica alpina, and 

 Phleum alpinum. But along the course of streams and 

 among rocks considerable changes take place. In crevices 

 of rocks within this region Saxifraga nivalis and Myosotis 

 alpestris are luxuriant ; but I have never seen them below 

 the true alps in open places or on smooth surfaces. We 

 can only get a true series by comparing the sequence of 

 species in similar situations. Cardamine pratensis, Trol- 

 lius europasus, Pyrola rotundifolia, and other species of 

 the plains, grow vigorously here under protection of rocks. 

 In such situations, if frequented by sheep, we still find 

 Urtica dioica. A good many trees and shrubs fail here. 

 Whether any species of rose or shrubby bramble should 

 be referred to the subalps I am doubtful. They certainly 

 approach near, although seldom. Pyrus Aucuparia, Betula 

 alba (?), B. nana, Pinus sylvestris, Juniperus communis, 

 Erica Tetralix, E. cinerea, Arbutus Uva-Ursi, and some 

 species of Salix are arrested here. I believe this is the 

 true limit of Betula alba, though I have seen a young 

 specimen above the line of Calluna vulgaris on Ben Nevis, 

 in a damp shaded ravine or glen where the line of the 

 Calluna was depressed at least a hundred yards. 



5. The Alpine Region is seen only in Scotland, unless 

 the highest peaks of the Snowdon range in Wales be re- 

 ferred to it. In the scale it is fixed to commence where 

 Calluna vulgaris ceases. This is a tolerably good test, 



