VEGETATION OF EOCKS AND WALLS 289 



lensis, or a variety of the alpine form -e.g., Arenaria 

 verna var. Gerardi. 



Many lowland plants grow in the more sheltered places, 

 even to the summits of the highest mountains. They are 

 often dwarfed, and some 'e.g., Poa annua and Festuca 

 ovina seldom produce flowers, but multiply vegetatively 

 (see p. 160). The following list, compiled largely from 

 Williams 's High Alpine Flora of Britain* shows the 

 highest range of the plants, usually in the Scottish 

 Highlands : 



Viola palustris, 4,000 feet. 

 Galium saxatile, 4,000 feet. 

 Euphrasia officinalis, 3,980 feet. 

 Bumex Acetosa, 3,980 feet. 

 R. Acetosella, 3,980 feet. 

 Ranunculus acris, 3,980 feet. 

 Achillea Millefolium, 3,980 feet. 

 Poa annua, 3,980 feet. 

 Cardamine flexuosa, 3,900 feet. 

 Taraxacum officinale, 3,900 feet. 

 Solidago Virgaurea, 3,900 feet. 

 Campanula rotundi folia, 3,800 feet. 

 Cardamine hirsuta, 3,800 feet. 

 Festuca ovina, 3,770 feet. 

 Thymus Serpyllum, 3,700 feet. 

 Caltha palustris, 3,600 feet. 

 Veronica serpylli folia, 3,500 feet. 

 Adoxa Moschatellina, 3,500 feet. 



Lychnis dioica, 3,500 feet. 

 Tussilago Farfara, 3,500 feet. 

 Oxalis Acetosella, 3,480 feet. 

 Viola lutea, 3,450 feet. 

 Agrostis canina, 3,400 feet (Carran- 



tual, Ireland). 

 Chrysosplenium oppositifolia, 3,4CO 



feet. 

 Heradeum SpJiondylium, 3,300 



feet. 



Stellar ia uliginosa, 3,300 feet. 

 Potentilla Tormentilla, 3,300 feet. 

 Mercurialis perennis, 3,300 feet. 

 Sagina procumbens, 3,290 feet. 

 Viola Riviniana, 3,000 feet (Car- 



rantual, Ireland). 

 Lotus corniculatus, 2,800 feet. 

 Anemone nemorosa, 2,750 feet. 



On dry exposed rocks the only vegetation consists of 

 close-growing lichens and minute mosses ; there is neither 

 sufficient water nor nutriment to support flowering plants. 

 On dry rocky summits, too, vegetation is scarce. Lichens 

 e.g., Cetraria islandica and species of Cladonia and 

 the woolly fringe-moss (Ehacomitrium lanuginosum) are 

 usually common. The latter occasionally forms a thin layer 

 of peat in which a few starved and stunted flowering plants 

 become established e.g., Empetrum, V actinium, Lyco- 

 podium Selago, Potentilla Sibbaldi, Gnaphalium supinum, 

 Azalea procumbens, Salix herbacea, Juncus trifidus, Car ex 

 rigida, Festuca ovina. All except the last three are low- 

 lying plants, which form a mat close to the ground, and 

 so escape the full force of the wind. 



* In Annals of Scottish Natural History, 1908-1910. 



19 



