The Botany of Iceland - 01.12.1932, Page 12

460
POUL LARSEN
spreading, especially when, as in the present case, the oceans set up
barriers to their migrations. And yet, since the fungi of Iceland
are in the main identical with those of the surrounding countries
(in so far as the vegetation with which the fungi are associated is
common to both), this shows tliat an exchange of fungi must have
taken place.
It seems very unlikely that the spores of the fungi could liave
been carried, either by direct spreading or by means of currents in
the air, across the great stretches separating Iceland from the nearest
countries, in such large quantities that tliey would be likely to reach
localities where conditions of germination were present.
It is much more likely that the spreading of the fungi takes
place indirectly. Detached fragments of phanerogams containing
living parts of fungi may be carried along by the wind during heavy
snowstorms and be swept over the polar ice, which generally in the
winter bridges over the seas between the lands in arctic regions and
also sometimes reaches the coasts of Iceland.1
There are, however, other ways by which the fungi may travel.
After the settlement of Iceland many culture plants have been intro-
duced into Iceland and with them no doubt many fungi. In the
following we shall mention some quite recent examples of such an
immigration of fungi. During the recently awakened interest in
horticulture in Iceland, which even went as far as the planning of
coniferous plantations, (a project that had to be given up, however,
after several unsuccessful trials), a number of plants were introduced,
which have since become infested with species of fungi previously
unknown in Iceland. These fungi, therefore, have probably been
brought into Iceland with the host planls.
This applies to the following species:
Lophodermium pinastri. .
Pliyllosticta Pseudacori . .
Phoma endolenca..........
Aposphaeria glomerata j
Coniothyrium olivaceum J
Phoma tingens............
on Pinus montana
- Iris germanica
- Alnus glutinosa
. Ulmus montana
- Aconitum sp.
1 J. Lind, The Geographical Distribution of some Arctic Micromycetes. Det
Kgl. Danske Vidensk. Selsk. Biologiske Meddelelser, VI, 5. Copenhagen 1927.
R. Sernander, Den skandinaviska vegetationens spridningsbiologi. Upsala
1901.