The Botany of Iceland - 01.12.1914, Side 122

306
THORODDSEN
Empetrum nigrum — a miserable stunted specimen of each of these
two species, 2 and 2’/2 crn. in height respectively. On tlie plateau
towards the east: Kjarrdalsheidi near Lón (665 metres), Salix
herbacea, Polygonum viviparum, Oxyría digyna, Ranunculus glacialis,
ail small and stunted. Markalda (961 metres) near the eastern
edge of Vatnajökull, Polygonum viviparum, Armeria maritima, Satix
herbacea, Saxifraya nivalis. Litla Snæfell (1133 metres), Salix her-
bacea, Oxyria digyna, Arabis alpina, Ranunculus glacialis. On Hlid-
arfjall near Myvatn (790 metres) where I was together with Grön-
lund in 1876, we noted the following plants: —Alsine biflora, Draba
nivalis, Saxifraga cernua, Cassiope hypnoides, Pedicularis flammea,
Oxyria digyna1.
All that is situated outside the glacier-bearing mountains in the
centre of Iceland at an altitude of 650—1100 metres may justly be
regarded as a desert; seen both from a geological and geographical
point of view the country here is desert-like in character, and in
spite of considerable precipitation the plants suffer from drought,
because the water disappears immediately over large areas owing
to the porous nature of the rocky substratum — lava, tuff, volcanic
gravel and sand. The few plants wliich grow in these wastes occur
widely scattered; at a height of 900—1000 metres above sea-level a
few lichens and mosses are seen only here and there, and at long
intervals a few specimens of the hardy Armeria maritima, Silene
maritima and Polygonum viviparum and in places where blown sand
occurs a few tufts of Elymus arenarius; at a height of 1000—1100
metres one may ride for miles without coming across a single pha-
nerogam. In addition to want of water, the frequent storms, often
of sand and snow, check plant-growth during the short summer;
moreover, a rather dry Föhn wind often blows across the wastes
north of the great Jökulls, having already deposited its moisture
upon the great plateaus of the Jökulls. Somewhat lower down, at
an altitude of 700—900 metres, a few more species are met with
as scattered individuals, e. g. Silene acaulis, Arabis alpina and A.
petrœa, and here and there a few haulms of Luzula arcuata, Poa
glauca or Festuca ovina; moreover, a few scattered cushions or tufts
of lichens (Stereocaulon) or mosses (Grimmia) occur.
Scattered here and there in these extensive wastes are sometimes
l See also Chr. Grönlund’s list of plants from Heljardalsheidi and Hrafn-
tinnuhryggur, and the list of plants collected by Johnstrup on Dyngjufjöll (Karak-
teristik af Plántevæksten paa Island, 1884, pp. 28 and 29).