The Botany of Iceland - 01.12.1945, Blaðsíða 85

THE VEGETATION OF CENTRAL ICELAND 427
snow-covering is both deep and long-lasting. Analysis XII, 3 was taken
near analysis 5, but in a locality in which the snow-covering was much
thinner and did not linger so long. In the snow-patch there is a closed
phanerogamous vegetation, and Anthelia is of no importance. Cassiope
hyþnoides dominates physiognomically together with Salix, and has a
similar degree of covering, Sibbaldia, too, is conspicuous. The whole
phanerogamous vegetation is much more strongly developed than in
analysis 5, which clearly shows the unfavourable influence on the
vegetation of the long-lasting snow-covering here. Analysis XI, 7 was
made on Eyjabakkar, c. 700 m above the sea. It agrees with analysis
XII, 3, and both may be said to represent a variant of the Sal. herbacea
association rich in Cassiope. On Eyjabakkar lichens in considerable
quantities are found in the snow-patch vegetation. Analysis XI, 7 was
made in a locality with a southeastward exposure in a snow-patch in
which an opposite slope, that is to say, a slope facing northwestward,
exhibited a marked Anthelia crust with very few and scattered phanero-
gamous individuals. Analysis XII, 6 is from Síðumannaafrjettur, from
the bottom of a fairly deep snow-patch, in the higher-lying part of
which analysis XII, 2 was taken (cf. association 8). The snow-covering
is much thicker and longer-lasting at the bottom than on the sides of
the snow-patch, and a comparison between these two analyses show
the difference that may result from different snow-coverings. The
number of species is almost the same in the two analyses, but the
spectra show that both the A and Ch percentages are higher in XII, 2
than in XII, 6. Analysis XII, 4 is from a snow-patch on Varmafell
on Síðumannaafrjettur c. 500 m above the sea. This snow-patch is
very damp, and Carex lagopina is so prominent that we may speak of
a variant rich in C. lagopina.
This association is widely distributed in the higher-lying snow-
patches throughout the area investigated. It is also met with in the
lower-lying places where the snow-covering is deepest and most long-
lasting. Thus it is very common in Víðidalur above 700 m altitude. If
the snow-patches there were very damp, Philonotis cushions might be
met with. Of phanerogams which are of frequent occurrence in that
kind of snow-patches the following may further be mentioned: Ceras-
tium trigynum, Saxifraga stellaris, S. nivalis, Poa alpina, and Deschamp-
sia flexuosa, all of which are fairly constant. Unfortunately I have no
analyses from these snow-patches.
If we compare this and the following two associations on the one
hand and the other snow-patch associations on the other, it appears
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