The Botany of Iceland - 01.12.1914, Side 125

PHYSICAL GEOGRAPHY
309
deserts — which are as yet very little known, e. g. Thorláksmvrar,
Mariutungur and Eyjabakkar (672 metres). I visited the last lo-
cality in 1894 and found there extensive areas covered with Cype-
raceæ, cotton-grass and other plant-growth. In Fjallasveit, east of
Jökulsá, a parish situated up on the plateau at an altitude of 400—
500 metres, the population of which is solely dependent on sheep-
rearing for their sustenance, very large tracts are covered with blown
sand which in many places is densely overgrown with Elymus
arenarius, Salix lanata, S. glauca and Juncus balticus, while Carex
incurva grows abundantly on damp sandy flats. Near the farm-
stead Yidirhóll (415 metres) I collected in 1895 the following plants: —
Juncus balticus, J. triglumis, J. trifidus, Elyna Bellardi, Carex incurva,
C. capitata, C. capitlaris, C.vulgaris, C.rigida, C.rariflora, Poa pra-
tensis, P. annua, Phleum atpinum, Festuca rubra var. arenaria, Cala-
magrostis stricta, Trisetum subspicatum, Selaginella spinutosa, Salix
lanata, S.glanca, Saxifraga aizoides, Gentiana tenella, Pleurogyne rotata.
North of Hofsjökull, at an altitude of 600—800 metres, similar
barren wastes occur, as around Odádahraun, consisting of ice-stri-
ated doleritic lava, and here also the individual plants occur widely
separated, but, in the neighbourhood of stream and lakes, the oases
are larger both in number and size. The vegetation of these oases
is generally confined to small swamps and pools and sometimes to
rather extensive mountain-bogs; in the pool-vegetation Eriophorum
is usually dominant, but sometimes Carices are in the majority. In
mountain bogs numerous large knolls (dys) often occur which are
usually dry at the top and covered with mosses and various rocky-
flat plants, but wet below and overgrown with swamp-plants. Dry
tracts between the swamps are generally covered with Grimmia-
heaths which sometimes pass into lichen-heaths. Of the oases oc-
curring in these districts may be mentioned: Sydri Pollar, Nyrdri
Pollar, Geldingaá and Laugafell (with hot springs), and southwards
near Sprengisandur, on tlie eastern side there is Nyidalur, and on
the western side Nauthagi and Arnarfell with an unusually luxuri-
ant vegetation which has been described by St. Stefánsson1, who
also describes the plant-forinations near Laugafell and Geldingaá.
In Nydri Pollar (704 metres) I collected in 1896 the following
plants: Poa alpina, P. /lexuosa, Carex rigida, Eriophorum angustifolium,
Salix lanata, S. glauca, S. herbacea, Pedicularis flammea, Tofieldia
1 Geografisk Tidsskrift, XVI, 1902, pp. 230 and 231.