NOTES ON THE FLORA OF SHETLAND 267 



Cochlearia alpina was also in full fruit on plants 1 to 2 in. 

 high. 



In some of these flatter areas of Serpentine, where the rock 

 seems to weather rapidly, the percentage of bareness {areas with- 

 out any plants) was about eighty, that of the plants about twenty; 

 it is here where most of the rarer alpine plants occurred. The 

 fertile spikes of all the sedges but Car ex flava were somewhat 

 nigrescent, some markedly so, the plants themselves being very 

 dwarfed. This area was also practically destitute of Muscineae ; 

 the only Bryophytes noticed were a small Trichostomum, a form 

 of Webera nutans with tiny patches of Bhacomitrmm lanuginosuni, 

 and these were near small abutting stones. 



A very noticeable feature on some of the wind-swept moor- 

 lands was the dominance of Bhacomitrmm lannginosum (Grimmia 

 hypnoides), beds of the old plants often forming a mat of a foot or 

 more in thickness ; in dry weather these tussock-like masses could 

 be easily recognized a thousand yards away. The somewhat 

 larger size and deeper colour of the flowers of Lychnis dioica were 

 very marked, and reminded one of Norwegian forms. 



Particular notice was taken of two very small planted woods, 

 one in Unst, the other on the Mainland. Acer Pseudo-plataniis 

 was the chief tree planted, but on the border there were one or 

 two plants each of Ulmus campestris, Pyrus Aucuparia, Cytistcs 

 Laburnum, one plant each of Fraxinus excelsior and Symphori- 

 carpus racemosus, and in one of the woods a species of Salix, like 

 a broad-leaved viminalis. For protection from the wind a wall 

 had been built around them, but above the line of the wall the 

 wood became pulvinate, after the style of the gorse and heather 

 on wind-swept tracts, as on the high parts of Anglesea south of 

 Holyhead. Many of the leaves were curled and brown at the 

 edges. Above this compact cushion-like mass small dead branches 

 of Acer were projecting (as seen at a little distance). The trees 

 bore in abundance some of those crustaceous corticolous lichens, 

 which are able to live in such situations, on their very shaded 

 trunks, such as Opegrapha atra ; this shows without much doubt 

 that the spores of hchens must be carried great distances by the 

 wind. 



Some Plant Associations. 



To give an example in some detail of an association, some 

 extent of the Serpentine in Unst at 130 to 150 ft. elevation, which 

 was fairly well covered by a turf, was carefully examined with the 

 following result ; the numbers apply to percentages : — Thymus 

 Serpyllum (16), grasses, mostly viviparous Festuca ovina, dwarf 

 Agrostis and Molinia (12), Galluna (8), Linum catharticum (7), 

 Carices, mostly glauca and panicea (6), Selaginella (5), Plantago 

 maritima var. lanata (4), Scabiosa succisa (about 3 in. high) (1), 

 Bhinanthus (only 2 to 3 in. high) (3), Thalictrum alpinum (3), 

 Scilla verna (2)— the rest, in smaller quantities than the above 

 (30). It consisted of scattered and very dwarf plants of Sieglingia, 

 Anthyllis, Habenaria viridis, and a few others in less quantity 

 still, often odd plants, such as unifloral Potentilla Tormentilla, 



V 2 



