354 TRANSACTIONS OF THE [Sess. lxxix. 



sand. Similar mats are found in the same part of the flats, 

 formed of Calluna vulgaris, var. pubescens, Hull., which 

 has a hoary appearance, due to the covering of the stem 

 and leaves with close, short, whitish hairs. It is to be 

 expected that such a condition, with its help in reducing 

 transpiration, should be found in a plant growing on open 

 sand, exposed to sun, wind, and defective water supply, so 

 corresponding with the fleshy condition in the neighbour- 

 ing littoral plants, which defends them against the same 

 danger arising in a different environment. This hairy ling 

 grows elsewhere on the fixed dunes of the Culbins ; nor is 

 it peculiar to the sands, for it is to be found on the heaths 

 of the hills inland, near Pluscarden, and in the forest of 

 Altyre. 



The cushion condition which is so well shown in these 

 Callunas, both the common one and the hairy variety, is, 

 still more than hairiness, a striking feature of the flora 

 generally on the fixed dunes. The long, single main stem 

 branches profusely at the surface of the sand, the branches 

 spreading horizontally. 



On the same flats as the Callunas, but at other parts, 

 are somewhat similar circles of Rumex Acetosa, Linn. 

 " Pads " of Juncus squarrosus are found in most parts of 

 the flats. 



Mosses are prominent in the vegetation of the Culbin 

 Sands, frequently being first to colonise the settling sand. 

 They have much effect in binding the sand, as is found 

 when an attempt is made to remove a specimen from the 

 firmly matted mixture of moss and sand under the surface. 

 Mosses are in some places the only vegetation on the sand ; 

 but also, where there is a close covering of angiosperm 

 plants, mosses are commonly to be found underneath the 

 taller herbage, spreading densely over the surface of the 

 soil. Lichens play a similar but less extensive part and 

 show a lesser number of species. 



In the neighbourhood of the Callunas, Bryum, sp., takes 

 a leading part in initiating the sand-binding. The lichen, 

 Peltigera canina, Hoffin., dominates much of the sand 

 alone, and Cladonia rangiferina, Nyl. ; and Cladonia 

 pyxidata, Fr., also cover much space. 



Burnside flora. — Three small burns cross the flats, 



