ALPINE VEGETATION ON BEN-Y-GLOE, PERTHSHIRE 235 



spinulose points al)Ove the moss. Cciraria crispa straggles up 

 through the mats, singly or in dense tufts. Its margins are beset 

 with cilia, giving it a distant resemblance, on a larger scale, to 

 the eroded leaf-margin of the dominant moss. In dry weather 

 the thallus rolls up and becomes subtubular. Some of the large- 

 branched Cladonice have perforate axils, the orifices being at times 

 spinulose, the spines acting as water conductors to the interior of 

 the hollow podetia. A lichen almost confined to this association 

 is Alectoria nigricans, and the allied A. ocliroleuca is also partial 

 to it. They resemble miniature trees. The trunks obtain support 

 by standing buried in the Ehacomitrium, the branches rising above 

 the surface, where they ultimately become dark and discoloured by 

 exposure to sun, wind, and frost. In dry weather they are readily 

 overlooked, but under moister conditions their entangled ramuli 

 and slender branchlets become everywhere studied with tiny drops 

 of dew, and are then very noticeable. When dry they are rigid 

 and brittle ; then the feet of the alpine hare or ptarmigan readily 

 crush them into small particles, to be disseminated by the wind. 

 In this manner this rare lichen is probably propagated ; its fruit 

 is unknown with us, but has been found, according to Crombie (7), 

 in Labrador and Arctic North America. 



It must be observed that this list of species applies only to the 

 Upper Arctic-Alpine formation of Ben-y-Gloe, and that had we 

 been dealing with the similar formation of the micaceous debris 

 of Ben Lawers, or granitic detritus of the Cairngorms, we should 

 have a very different list of species, and in the case of the former 

 a very much richer one. Such beautiful plants as Solorina crocea 

 on Lawers, and Platysma nivalc on Braeriach, with many others 

 as rare if not so handsome, would reward the explorer of the 

 Arctic-x\lpine area of those mountains. A comparative list of 

 plants from the various summits above 3000 ft. would provide 

 exceedingly interesting matter for speculation. 



References. 



(1) A. G. Tansley and G. E. Moss : Types of British Vegeta- 

 tion. 1911. 



(2) E. Smith : Botanical Survey of Scotland. Scott. Geog. 

 Mag., 1904. 



(3) W. G. Smith : Anthelia, an Arctic- Alpine Association. 

 Scott. Bot. Keview, No. 2, April, 1912. 



(4) S. M. Macvicar: The Distribution of Hepatics in Scotland. 

 Trans. Bot. Soc. Edin. xxv., 1910. 



(5) C. B. Crampton : The Vegetation of Caithness considered 

 in Eolation to the Geology. 1911. 



(6) J. Crombie: Grevillea, i. p. 62, and viii. p. 112. 



(7) J. Crombie: Monograph of British Lichens, part i., 1894. 



