Floras of Great Britain and Central Europe.  9' 
But the absence of Vaccinium uliginosum appeared to me even 
more remarkable (Oxycoccus ranges from Somerset to northern 
Scotland). The so-called “Moorbeere” (Vaccinium uliginosum), 
which is never absent from German “Hochmoor,” either on the 
northern plain or the mountains, which lives on the sand-dunes of 
the North Sea islands, and which, in the mountains from 700 m. 
upwards, suppresses Vaccinium Myrtillus and Vitis-Idea, is quite 
absent from the south of Great Britain, occurring only from Durham 
and Westmoreland northward to the Orkneys. But even in Scotland, 
in the parts visited by us, I never saw the plant, though I was on the 
look-out, so that it cannot be social and abundant. It shares the 
distribution of Linnea, and thus with that plant and Arctostaphylos 
Uva-ursi unites the second and third groups of stations of northern 
plants given on p. 244. Andromeda polifolia, on the other hand, 
occurs so far south as Norfolk and Somerset. 
Low ALTITUDINAL LIMITS OF THE FORMATIONS. 
The altered scenery with the uncommonly low occurrence of 
boreal-arctic species in the mild winter climate of Great Britain is 
unquestionably ecologically facilitated by the damp stormy summers 
which have suppressed the growth of trees. In our excursions in 
the Pennines I saw even in deep sheltered clefts, besides weak 
dwarf trees of Quercus sessiliflora and Betula pubescens, only massive 
stems of Sorbus Aucuparia laden with red fruit: 100 m. higher 
nothing but “ Hochmoor ” covered the flat-topped summits and 
ridges. On free slopes we found as low as 250 m., between Pteridium 
and Agrostis, great masses of Empetrum nigrum. I recall that 
Empetrum occurs also on the German coast where it is exposed to 
damp sea-winds, and sparingly on sandstones in Saxon Switzerland 
at about 300 m. where damp rock clefts covered with Sphagnum 
afford a moist and cool mountain climate. But in general Empetrum 
does not occur on peat-moors below 700 m. and becomes abundant 
at about 1000 m., growing mostly at and above the tree-limit on 
free summits in the sun. ' 
A great difference would be introduced into the physiognomy 
of the vegetation if Picea excelsa were a definite component and 
formed a considerable zone between the uppermost deciduous trees 
and the arctic-boreal associations of dwarf shrubs. In Central 
Europe also, if the Spruce is absent, the grass, heath and moor 
formations generally descend to lower altitudes. In Hercynia I 
recall the magnificent meadows above the beechwoods of the 
