258 TRANSACTIONS OF THE [Sess. lxxviii. 



and stunted, and is overtopped by Nardus stricta, Linn. ; 

 Deschampsia flexuosa, Trin. ; Juncus squarrosus, Linn. ; 

 and Scirpus caespitosus, Linn. To such an extent, indeed, 

 do these four species prevail, that the dun colour of the 

 inflorescences and withered leaves of the grasses, combined 

 with the deeper and more yellow tint of the tops of the 

 rushes, gives to the hill that distinctive colouring which has 

 earned for it the name of " Blair Buidhe," or the " yellow 

 moor." 



On Stronyaraig ridge, and on Leacann nan Gall, where 

 the elevation is from 1700 to 1900 feet, the vegetation 

 consists chiefly of the following species : Empetrum 

 nigrum, Linn. ; Vaccinium Myrtillus, Linn. ; V. Vitis- 

 Idaea, Linn. ; Juncus squarrosus, Linn. ; Festuca ovina, 

 Linn. ; Agrostis canina,. Linn. ; Deschampsia flexuosa, 

 Trin. ; Nardus stricta, Linn. ; Eriophorum vaginatum, 

 Linn. ; Galium saxatile, Linn. ; Potentilla Tormentilla, 

 Scop. ; Sphagnum, and Polytrichum. In dry, stony situa- 

 tions grey lichens and soft hoary tufts of Rhacomitrium 

 are the principal occupants. 



Only when one reaches the stony top of Cruach nan 

 Capull, which attains its highest point at an altitude of 

 2005 feet, are any distinctively alpine plants to be found. 

 Here, in the coldest and most wind-swept situation, creeping 

 low among the stones, are found, among a sparse and 

 stunted vegetation, Lycopodium Selago, Linn. ; L. alpimim, 

 Linn. ; and Salix herbacea, Linn. 



Adaptations. — The plants which have been enumerated 

 present some typical examples of the modifications to be 

 met with in the floras of regions of physiological drought. 

 The o-eneral prevalence of the ericoid habit, seen in the 

 shrubby form and small inrolled leaves of Calluna, Erica, 

 and Empetrum, and in the mycorrhiza of Calluna and 

 Orchis, is perhaps the most salient character. The condi- 

 tions as regards exposure closely resemble those of the 

 shore, but the presence of abundant soil-moisture is in strik- 

 ing contrast, while in the check to absorption imposed by 

 the acid humus and want of aeration of the peaty soil there 

 is ao-ain an approach to the condition of the salt-marshes. 

 Corresponding with these resemblances and differences in 

 environmental conditions, similarities and contrasts may be 



