STUDIES ON THE VEGETATION OF ICELAND 89 
Thalictrum alpinum. Of minor importance are Festuca ovina, F. rubra, 
Cardamine pratensis, and Empetrum nigrum. 
Where the ground-water covers the soil throughout the year 
the knolls disappear, the surface is level, and the flöi vegetation is 
formed (cf. table 20,7). The dominant species are Eriophorum poly- 
stachyum and Carex chordorrhiza. 
D. NORDTUNGA. 
In the preceding part we have dealt with all the lowland types 
of vegetation except the forest. In the following I shall give a 
description of it in so far as I was able to examine it during a 
couple of days’ stay on the farm Norötunga in Borgarfjordur. 
Here the forest occurs both at the bottom of the valley and on 
the sunny northern slope, but not on the shady southern slope. 
The succeeding investigations, however, apply especially to the forest 
at the bottom of the valley. 
Viewed from one of the valley slopes the forest does not appear 
as a continuous growth in the sense that the trees are equally di- 
stributed over the entire area of growth, but open patches where 
the birch is low, very scattered, or entirely absent, alternate with 
stretches where the growth is denser. It was, however, especially 
on the outskirts that this was the case, in the interior of the forest 
the growth was continuous. 
Fig. 14 shows a glade in the forest. The soil is full of large 
knolls. 
The statistical results are given in table 21 A. Nos. 1—2 are 
from the forest itself, 3—6 from the glades in the forest, No. 7, 
finally, is the mo some distance outside the forest between the latter 
and the farm. 
On the forest-ground proper grasses are dominant, the following 
being the most numerous: Deschampsia flexuosa, Anthoxanthum 
odoratum, Agrostis canina and A. tenuis, further Festuca rubra; of 
herbaceous plants there occur Thalictrum alpinum, Carex rigida, 
Galium boreale and Normanni, and Polygonum viviparum. The 
chamaephytes are of minor importance, Vaccinium uliginosum and 
Empetrum nigrum are found here and there. 
The vegetation of the glades occupies an intermediate po- 
sition between the forest-ground and the mo. The species known 
from the forest-ground recur here, moreover a number of typical 
