The Botany of Iceland - 01.12.1945, Blaðsíða 114

456
STEINDÓR STEINDÖRSSON
rich in Vaccinium; this species was not otherwise found in the Grim-
mia heath of the highland.
6. THE FELL-FIELD SERIES
All the formations referred by me to the fell-field series have the
character in common that the vegetation is open, occurring only in
small tufts, often at rather large intervals. The snow-covering is, as
a rule, thinner than in other formations of the highland, and the soil
is dry. An exception is, however, formed by the moraine vegetation.
However, these conditions vary within the different formations, and
their physiognomy differs entirely according to the nature of the soil,
more especially according as it is covered by sand, clay, or gravel, or
by bigger or smaller stones; finally, the moraine is in a class apart. Still
these formations have a character in common; they are all unstable,
to an even greater extent than the other formations of the highland.
Thus the flag, the sand, and the gravel flat (melur) may all be either
in progression or in regression, their vegetation may be about to be
destroyed or to be removed by the wind, or they may be at the point
of being covered with vegetation, their vegetation may be increasing,
and each of them may later be converted into a heath or perhaps a
mýri formation. In most cases it is impossible to decide from a single
observation on which side of the vegetation cycle the individual locality
is found. The moraine, however, occupies a peculiar position; thus
where the vegetation is progressing, new formations are developing on
areas formerly covered by the glacier.
a. The Flag Vegetation (clayey flat vegetation).
The formation here termed flag differs from that described by
earlier authors under this name (cf. Molholm Hansen í93°, p.
70 ff). Molholm Hansen (1930, p. 180) describes the flag
vegetation as follows: “The surface is a bare clayey flat with scattered
knolls and stones. The vegetation is characterised by its high therophyte
percentage. ... Arctic species are more dominant in flag than in jaðar
or especially valllendi”.
(Table XIX. A-B).
A common feature of the flag vegetation described by me here and
that described by Molholm Hansen is that it is found on “clayey