The Botany of Iceland - 01.12.1912, Page 81

MARINE ALGAL VEGETATION
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neither, is any distinet boundarv found between the boreal and
subarctic íloral districts, and tbe north and north-west of the country
must, strictly speaking, be considered a large boundary-area, a view
which accords well, also, with the hydrographic conditions. Here,
the boreal, subarctic and arctic species intermingle.
At the south-eastern point of Iceland there is, on the other
hand, a rather distinct hydrographic boundary along the stretch
from Vestrahorn to Ej'strahorn (or Lónsheiði). The greater part
of this coast is sandy, and difflcult of access for the investigation
of the algal vegetation. From my own observations I can only say
that Berufjörður, the most southerly point in E. Iceland whicli I
have examined with regard to its algal vegetation, has a cold-water
flora, and that the Vestmannaeyjar, the most easterly Iocality on the
south coast which I have examined for the same purpose, have a
warm-water flora. The houndary must lie between them, and I
conclude, especially from the hydrographic conditions and the dis-
tribution of the Plankton-associations, tliat it is situated just on tlie
stretch of coast already mentioned. Ove Paulsen (55 and 56) has
given valuable information respecting this boundary, and it is
evident from his investigations that the boundary varies to a slight
extent, tlie facts being that in May-June it has been found in the
vicinity of Eystrahorn (see 55, map I), but in July-August at Vestra-
horn (see 55, map II). If algæ grow on this stretch of coast, one
may conclude that there exists a mixed flora resembling that of
N. and NW. Iceland. Whether boreal species can be carried to E.
Iceland in this manner is at present not easy to say with certainty,
yet it seems to me that the occurrence of Dumontia filiformis and
Delesseria sanguinea, both of which are absent in N. and NW. Ice-
land, can be most easily explained in tliis way.