Rit (Vísindafélag Íslendinga) - 01.06.1975, Side 155

is indicated by the presence of Comarum palustre. Gramineous and
herbaceous plants often extend into the jaðar. J. filiformis is domi-
nant in physiognomy, but C. nigra is similar in covering. I have
observed a closely related sociation on a few sites where C. nigra
is replaced by C. Bigelowii and I have named it accordingly.
95. J. filiformis — Eriophorum angustifolium sociation
(Tab. XXI A-B 6)
The only existing observation is from Bolungavík, but this socia-
tion is fairly widely distrihuted in Vestfirðir. It is, however, not
clearly distinguishable from Nardus sociations. The snow cover is
fairly thick. Sphagnum is abundant, but hardly any other kind of
moss occurs. The sociation has unmistakable jaðar characteristics,
since it occurs almost exclusively along a narrow strip on the
borders of mire tracts.
c. Equisetum palustre jaðar (Equisetétum palustris)
Tlie second main division of the jaðar is the Equisetum palustre
jaðar, but whereas the Juncus jaðar is almost invariably associated
with the mýri, the Equisetum jaðar is adjacent to the flæðimýri or
the C. Lynghyei flói, which are often hard to separate as men-
tioned earlier.
The Equisetum jaðar is either flat or finely patterned. The ter-
rain is moderately moist and the jaðar is located between flæðimýri
and elevated grassfield patches, or sometimes on low mound-ridges
within the flæðimýri proper. (Steindórsson 1932 p. 17 ff.), but its
surface is somewhat more elevated than that of the flæðimýri so
that it is not submerged, and most of it probably rises above the
ice-sheet which covers the flæðimýri in winter. The vegetative
cover is continuous and dense5 and there is but httle moss. The
environment as a whole seems to indicate favourahle growth condi-
tions since the jaðar base layer is formed in the same way as that
of the flæðimýri. At the highest points of the jaðar Juncus balticus
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