The Botany of Iceland - 01.12.1945, Síða 56

398
STEINDÓR STEINDÓRSSON
in the two places. In general it is more closely related to the lowland
mýri than to the alpine mýri, like the other associations on Síðuman-
naafrjettur. That it is also found in Fagridalur, is due, I suppose, to
the fact that the valley is well sheltered and the snow-covering com-
paratively thick; the association occurs here in places with a southern
exposure. On the whole it is remarkable that the vegetation of Fagri-
dalur has a more pronounced lowland character than the vegetation of
other localities on Brúaröræfi.
8. Carex Goodenoughii-Ass. (Tab. V. A-B, 8-10).
Although I include this association here, it actually does not belong
to the alpine mýri formation but to the typical lowland mýri. It was
only found in two places, Laugar and Hattver on Landmannaafrjettur,
but in both these places there are hot springs, and the heat of the soil
exerts a very strong influence on the vegetation, so that it exhibits a
perfect lowland character. This appears especially distinctly from
analyses 8-9, which i. a. include species of the southemmost plant
groups E2 and Ei, and in which Cardamine pratensis and Epilobium
palustre are among the dominant species.
In this connection it may be pointed out that all my observations
tend to show that Carex Goodenoughii, which is the character species
of the mýri formation in the lowland, is very rare in the highland, and
seems to thrive poorly at great altitudes, except where special conditions
prevail, as for instance the heat of the soil at Laugar and Hattver and
the exceptional shelter and snow-covering in Fagridalur. Something
similar seems to apply to Equisetum palustre; above an altitude of
500 m it, too, is rather rare. As far as I can see, Carex rigida is a sub-
stitute for C. Goodenoughii in the highland mýri; in the lowland
C. rigida is a marked xerophyte, but in the highland above 500 m it
is an important element in most mýri associations.
g. C. rariflora—Eriophorum polyslachyum—Salix glauca-mýri rich
in Sphagnum.
In Fagridalur there was a small area of mýri which differed phy-
siognomically from all the other mýri associations. Unfortunately I took
no analysis there, but I have my diary notes on it and two identified
moss samples. The mýri was relatively very damp, slightly inclined, and
with small knolls. The species most conspicuous physiognomically was