The Botany of Iceland - 01.12.1945, Síða 50

392
STEINDÓR STEINDÓRSSON
cur under very similar conditions and are very closely related. I am in-
clined to believe that the alpine mýri is hardly ever any stable forma-
tion, but a transitional form either from a damper to a drier stage, or
the reverse. Nobody who has observed the vegetation of the highland
can avoid noticing how changeable it is. Larger or smaller areas of
vegetation are either forming or disappearing. It is difficult to separate
pure associations within the mýri formation. Those I have attempted
to distinguish, should perhaps more correctly be called association frag-
ments or variants of the actual associations which occur in related
formations; but precisely this condition I regard as quite characteristic
of unstable plant formations in which typical associations have either
not developed or are changing into others.
If we compare the mýri formation with the types of vegetation of
the neighbouring countries, we shall no doubt find formations which
are closely related to the alpine mýri, whereas it is difficult to find
formations which are closely related to the lowland mýri of Iceland,
this mýri differing from both the Arctic and the European, especially
the Scandinavian, types of mýri.
In the “Græskjær” (grassy bogs) mentioned by both W arming
(1888, p. 130) and R o s e n v i n g e (1896, p. 243) from Greenland,
many of the same species are found which dominate in the alpine mýri
in Iceland. In addition to the two species of Eriophorum, Salix
glauca, Carex rariflora, and C. rigida are recorded; however, it is pre-
cisely these species which especially distinguish the vegetation of the
alpine mýri from that of the lowland mýri. Within Scandinavia I
should think that the closest relationship is to be found with the Carex
rariflora and C. rigida “Niedermoore” mentioned by Fries (1913,
pp. 132 and 134).
Large continuous areas of the mýri formation are not found in the
highland, it nearly always occurs as belts around the areas of flói at
the bottom of the valleys or in some few valleys along the foot of the
mountains. Thus for instance in Fagridalur, where a large variety of
the formations of the mýri series were found in the localities investigated
by me. In addition the mýri vegetation is sometimes found along brooks
and rivers where there is a fairly considerable gradient. In small depres-
sions we often find a patch of flói at the bottom surrounded by a nar-
row belt of mýri, and, at the top, a shrub heath.