1 905-1906.] Scottish Mountain Plants. 257 



one place, afterwards migrating. They rather appear to have 

 been evolved in response to environment, and form striking 

 illustrations of the influence of the mountain climate upon 

 the growth of plants differing widely in affinity and distrib- 

 uted over many countries. 



The cushions, often very regular in outline, are composed 

 of densely ramified branches so thickly placed that they 

 press each other on all sides. The shoots all reach to about 

 the same length, and are furnished with living leaves at the 

 tops only. The withered foliage of previous years on the 

 lower portion of the stems serves to absorb and retain 

 moisture in the cushion. In Scotland two good cushion 

 plants are not uncommon, the Cyphel (Arenaria Cherleria) 

 and the Moss Campion (Silene acaulis), the latter with small 

 pink flowers expanded just above the level of the leaves. 

 (Plate XXII., Fig. 2, shows a small plant in flower, and a 

 larger one with ripening capsules.) These two plants often 

 grow side by side both on the summits of many mountains 

 and on the higher parts generally. 



Cushion growths (except certain mosses) are absent from 

 the lowland floras of most countries, — hence the ground 

 where these forms are seen is likely to be either at a high 

 elevation or far north where many plants descend to sea- 

 level. Cushion plants also occur at low levels in the South 

 Temperate and Antarctic regions — e.g., Scleranthus biflorus, 

 living plants of which may be seen at the Eoyal Botanic 

 Garden, Edinburgh. 



[Thirty-three slides were shown in illustration of the above 

 paper. The photographs here reproduced from the author's 

 negatives illustrate some of the more prominent types of 

 native mountain vegetation.] 



EXPLANATION OF THE PLATES. 



Plate XXL Mountain scene (Perthshire). Early Spring. The snow has 

 disappeared from jjortions of the rocks, leaving many plants exposed. 



Plate XXII. , Fig. 1. Mountain shrubs : Heather (Calluna) with the Eed 

 Whortleberry (Vaccinium Vitis-Idaea), the latter creeping through sheets 

 of a hoary Lichen. 



