The Botany of Iceland - 01.12.1945, Síða 76

418
STEINDÓR STEINDÓRSSON
the late spring or the summer, or at any rate so long that the plants
in the surrounding localities have begun to grow long before the snow
in the snow-patch proper has disappeared, the vegetation will be scat-
tered and often poor in species, the bare soil is visible everywhere be-
tween the phanerogams or it is covered with a crust of liver-wort. How-
ever, this kind of snow-patches hardly occurs in the lowland except
in the coldest tracts, but they are very common in the highland. In
the highland and in the cold parts of the country the snow-drifts may
persist throughout the whole summer or till August, and as they lie
on slopes, the areas lying below them will, as a rule, constantly be
irrigated by the cold thaw-water, which makes the ground cold and
damp. In that kind of snow-patches the vegetation will be very scat-
tered and poor in species. Species as for instance Catabrosa algida,
Cerastium trigynum, Saxifraga nivalis, S. stellaris, Deschampsia alpina,
Carex lagopina, and, where the ground is especially stony, Ranunculus
glacialis occur. In such places in which the snow persists longest, the
snow-patch proper will be largely devoid of vegetation. Such bare
patches may be encountered everywhere on the higher-lying mountain
sides, in most cases, however, they are surrounded by a poor snow-patch
vegetation, consisting for instance of Salix herbacea, Gnaphalium supi-
num, Carex lagopina, and Epilobium anagallidifolium.
The formation called snow-patch formation in the present paper
is associated with places in which the snow-covering is abnormally
thick or lasts abnormally long, or both. I regard the snow-patches in
about the same way as J. M. N o r m a n in Norges arktiske Flora I
(Kria. 1894, p. 25), viz. as: “All localitíes, whether situated at a high
or a low level above the sea, whether lying near the margin of a
perennial snow-patch or found in a place where a snow-patch has
entirely disappeared, if only the snow has, at any rate, persisted till so
late in the summer that the spring vegetation of the nearest surround-
ings were in full bloom before the plants in the locality formerly covered
with snow have begun to sprout” (translated from the Norwegian).
The vegetation of the snow-patches varies greatly according to the
conditions prevailing in the different localities, the duration of the
snow-covering, the exposure, the height above the sea, etc. This ap-
pears clearly from the description of the individual associations. Un-
fortunately I have only very few observations from the localities in
which the snow persists longest, the “extreme” snow-patches.