370 
W. West and G. S. West. 
The cells of both upper and lower epidermis are greatly arched out¬ 
wards and strongly cuticularized. Stereome is scarcely developed, 
being present only at the extreme edges of the leaf and in very 
small amount. There is none even at the mid-rib. There are seven 
vascular bundles, each one possessing a double sheath consisting of 
an outer layer of large cells and an inner layer of small cells. The 
bundles have no vessels and no intercellular spaces. There are only 
three ridges (seen as rounded elevations in transverse section) on 
the upper surface of the leaf corresponding to the three median 
bundles. The mid-rib projects on the upper surface only. The 
mesophyll is compact and continuous, with very minute inter¬ 
cellular spaces, and all the cells contain chloroplasts. The stomata 
are disposed in about six rows on the upper surface and a single row 
near each edge of the leaf on the lower surface. The xerophytic 
characters of this grass are due mostly to the coldness at its roots 
and partly to continuous cold winds. 
The actual summit of Knutsho (5,602 feet) is a steep rocky 
mound of several hundred feet, the rock-surfaces being thickly and 
entirely covered with lichens. In the large holes of the great rocks 
was an abundance of the hepatic Chandonanthus setiformis, occurring 
in characteristic golden-green patches. Associated with it in some 
of the patches were Jungcrmannia Lyoni, Dicranum molle and Hylo- 
comium proliferum. The lichen Pilophorus robustus occurred here in 
fine fruit. In many of the crevices individual and tufted flowering 
plants occur. The following species were noticed to the very 
summit:— Saxifraga ccespitosa, Salix herbacea, Oxyria digyna, Poly - 
gonmn viviparum (without flowers), Luzula arcuata, Poa stricta, and 
Aira flexuosa var. montana. 
On the west side or Nystuhoerne side of the valley the shrub- 
land zone is not so dense, and as it passes into the alpine pasture 
there are a number of marshy and boggy places. Sibbaldia pro- 
cumbens was abundant in the detritus brought down by the snow, 
and was often associated with Gnaphalium supinum, as is the case 
in many of the Perthshire mountains. Eriophorum Scheuchzeri and 
Hieracium alpinum were often conspicuous, and among the gravelly 
soil was an abundance of fruiting Conostomum boreale. Great masses 
of Paludella squarrosa occurred alongside sheets of Hypniun sar - 
mentosum (in fruit), while on higher slopes of fine debris left by 
melting snow was an abundance of Polytrichum sexangulare among 
patches of Ranunculus glacialis. Splachnum vasculosum and 5. 
pcdunculatum were frequent on the old stercoral deposits of cattle, 
