Floras of Great Britain and Central Europe. 251 
basaltic summit of the Rhon ; and at the lower limit of the mountain 
woods in the Vosges, where dwarf communities of Fagus silvntica 
compete with mountain meadows. It appears to me certain that 
the Spruce spreads subspontaneously in the south of England 1 , like 
the Sycamore and especially the Pine, and that it might become 
fully naturalised : it would be of great interest to try by cultivation 
experiments how the tree would behave on siliceous hills of more 
than 400 m. in height, if it were able to defy the rainy stormy 
British summers. One would think it could not find worse 
conditions than on the swampy moory slopes of the Riesengebirge 
at 1200 m. 
The Higher Mountains. 
At such a height as this in Great Britain the dwarf shrub 
formations and the closed Nardetum has already been long super¬ 
seded by the Chomophytes, the ridge (“Grat”) formation or the 
associations on high mountain rocks, where, between dwarf willows 
and mosses, rare arctic species like Sagina nivalis on Ben Lawers 
have their isolated stations. 
If certain mountains in the Grampians or in Cumberland are 
ascended one finds first at a height of only about 250 m., surrounded 
by Pteridetum or Nardeto-Agrostidetum, sun-loving species such as 
Saxifraga aizoides , Cochlearia , Pinguicula and Selaginella, with 
Chrysosplenium in the mountain streams and round springs; not 
shade-loving species like Ranunculus aconitifolius and Mulgedium 
in the German mountains. Only at a higher level up to about 
600 m. the sides of the mountains are occupied by Calluna, after 
Pteridium has disappeared and given place to tufts of Cryptogramme 
at 400 m. The heaths of the mid-German mountains, on the other 
hand, at and above the tree limit (1000—1300 m.), attain a very 
strong development with Calluna and Vaccinium uliginosum, and 
Calluna alone is in Germany more dominant and more widely 
spread than in the British mountains which I had the opportunity 
of seeing. 2 Prom 500 to 700 m. the Nardetum, with Juncetum 
squarrosi, is at its strongest, and above this level Enipetrum, 
Alcheuiilla alpina and Pinguicula begin to be so abundant that the 
turf has as much right to be called sub-alpine sward as the similar 
community of Homogyne, Luzida sudetica and Trientalis in the 
German Mittelgebirge at 1000—1200 m. A greater abundance of 
characteristic species naturally occurs round the cold springs : thus 
1 I know of no evidence for this belief. [Ed. New Phyt.]. 
* In the Eastern Highlands of Scotland, however, Callunetum 
covers very wide areas on the mountain sides. Cf. “Types 
of British Vegetation/’ p. 113. [Ed. New Phyt.]. 
