The Botany of Iceland - 01.12.1914, Side 123

PHYSICAL GEOGRAPHY
307
found, at intervals of a whole day’s journey, some small oases with
a denser vegetation, in places where water is present, especially
springs which issue from under the edge of the lava-streams. I
propose to give here the names of some of these oases and their
height above sea-level, and add some notes on their vegetation, which
is generally very little known. As almost no notes are published
on the vegetation of the plateau I shall avail myself of this oppor-
tunity to give a list of the species I collected on some of these
oases, as they have never been visited by botanists. Some of these
plant-covered patches are only a few square metres in extent, and
the largest of them are perhaps as much as a square km. in area1.
These oases often originate around hot springs, the temperature of
whieh need not be very higli — somewhat higher, however, than
the mean temperature of the locality at which they rise. Thus NW.
of Vatnajökull there are oases near Gæsavötn, 929 metres above
sea-level, where the springs have a temperature of 5—7°C., and
near Marteinsflæda (744 metres) with spring-temperature of 35V20 G.
and near Hitalaug (672 metres) with a temperature of 33l/2° C.
Gæsavötn is the most highly situated of all the oases that I visited
in 1884; plant-growth occurs here in connection with pools and
springs; along the margins the vegetation is formed by mosses and
Salix herbacea with scatlered specimens of Pohjgonum viviparum,
Saxifraga stellaris, Oxgria diggna, Armeria maritima, Cerastium and
Poa, while Carices and Eriophorum form a fringe along the water’s
edge. Here I collected the following plants: — Equisetum arvense
var. alpestre, Calamagrostis stricta var. borealis, Aira alpina, Poa pra-
teusis, P. pratensis var. alpigena, Poa atpina var. vivipara, Carex in-
curva, Eriophorum Scheuchzeri, E. angustifolium, Salix phglicifotia,
S. herbacea, Polggonum viviparum, Oxgria diggna f. pggmœa, Ar-
meria sibirica, Saxifraga stetlaris f. pggmœa, S. decipiens var. grön-
tandica, Rannnculus hgperboreus, Cerastium arcticum, C. triggnum2.
From here I went to Hvannalindir near Kverkfjöll, the nearest
oasis towards the east, but it took nevertheless two days (17, 18 Aug.)
to reach it, travelling along the northern edge of Vatnajökull; along
the whole of this stretch of land there were almost no plants, until
at Jökulsá, 734 metres above sea-level, I found in the gravel a fairly
large quantity of Chamœnerium latifolium and Oxgria diggna.
1 In my work “Island, Grundriss d. Geographie u. Geologie”, 1906. there is a
map showing the desert-boundaries and the oases known.
2 Determined by Prof. Joh. Lange.