The Botany of Iceland - 01.12.1930, Side 128

118
H. M0I.HOLM HANSEN
number of chamaephytes attain a luxuriant deveiopment. The do-
minant species are Betula rtarta, Empetrum rtigrum, Salix glauca
and herbacea, and Vaccinium uliginosum; in some snow patches one
may likewise find Juniperns communis and Belula alpestris. All
species attain a vigorous growth and form a dense mat of shrub-
like vegetation. Beneath the chamaephytes there is a bottom layer
formed of species like Deschampsia flexuosa, Festuca rubra, Carex
rigida, Polggonum viuiparum, Thalictrum alpinum, Galium Normanni,
and a number of mo plants such as Thgmus Serpgllum, Drgas oc-
topetala, Silene acaulis, Armeria vulgaris, Juncus trifidns, Elgna Bel-
lardi, Luzula spicata and several others.
The Geranium silvaticum Belt.
This formation initiates the snow patch vegetation proper. As
stated above, it occurs on the steep sides of the large snow patches
and in the smaller ones on slopes having a southern and western
exposure.
H are considerably more dominant here than in the marginal
zone whereas Cli are of minor importance. The most conspicuous
plant is Geranium silvaticum (cf. fig. 25). Under this plant and mixed
with it there occurs a dense vegetation of Ch and herbs; Vaccininm
uliginosum, Salix herbacea, S. glauca, and S. phglicifolia, Empetrum
nigrum, Polggonum viviparum, Thalictrum alpinum, Equisetum ar-
vense, Carex rigida, Deschampsia flexuosa, Agrostis canina and A. te-
nuis, Festuca rubra, Hierochloe odorata, Anihoxanthum odoratum,
Phleum alpinum, Poa alpina, Rumex acetosa, Rannnculus acer, Viola
palustris, Taraxacum officinale, Galium verum, Alchemilla alpina, and
A. minor, and Sibbaldia procumbens.
The table shows more precisely the quantitative distribution of
the individual species. In the main the three Iocalities examined
by me are in accordance even though some few species deviate.
The deviations probably express differences of environment, but the
material is so small that there is no reason for a more detailed
discussion.
The Bottom Vegetation.
Covering the bottom of the snow patch, below the Geranium
belt and well marked off from it, there occurs a Salix glauca-
Gnaphalium supinum formation. This formation is somewhat
poorer in species than the Geranium belt ahove. The density of