The Botany of Iceland - 01.12.1930, Blaðsíða 79

STUDIES ON THE VEGETATION OF ICELAND
69
and Empetrum nigrum, and in less degree Salix phijlicifolia. Of
Cyperaceae Carex Goodenoughii, C. chordorrhiza, C. rariflora, and
Eriophorum polystachyum are particularly conspicuous. To tliese
must be added Polygonum viviparum and Thalictrum alpinum. Ot
the marsh plants Carex rostrata is the most important. Comarum
palustre, Menyanthes trifoliata and Equisetum limosum occur more
sporadically.
The Flói Vegetation. Table 16 A—B, 1—5.
The vegetation is not evenly distrihuted over the surface of the
mýri; a number of the species, especially the chamaephytes, are
peculiar to the knolls, others, the Cyperaceae, only occur in the
spaces between the knolls. Passing from the mýri towards the llói,
the spaces hetween the knolls grow larger and larger until the knolls
have quite disappeared and with tliem their vegetation.
In table 16 A—B are tabulated the circling results for all the low-
land localities investigated in Iceland, from Lýngdalsheiði, Björk and
Lækjamót. The reason why so few localities were investigated was
that the rainy summer of 1925 afforded very poor working con-
ditions. In spite of the few localities, the table gives interesting
and mutually agreeing particulars of the llói vegetation. Compared
with the mýri vegetation it is very poor in species, the number of
species being 2—4, the density 1—2. Geophytes and helophytic
Cyperaceae form the bulk of the vegetation, tlius especially Erio-
phorum polystachyum, Carex Goodenoughii, C. chordorrhiza and
C. rostrata. A few otlier species occur sporadically.
The greatest interest attaches to the biological conditions when
compared witli those of the mýri vegetation. The species group
spectrum sliows a strong concentration in the central part of the
spectrum from E 3 to A 1; the lower groups, and in part the upper
ones, are not represented in the spectrum.
This spectrum seems to he typical of vegetations on a water-
covered surface. The Subularia flag, whose vegetalion is covered
hy a waler layer as deep as that of the llói, has practically the
same species group spectrum as the ilói witli a large predominance
in the central part of the spectrum. The same is the case with
the highland ilói.
The statistical and hiological conditions of the llói are, as a
comparison of the respective tahles will sliow, a furlher development