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 that an exchange of fungi must have 
taken place. 
It seems very unlikely that the spores of the fungi could have 
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 they 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.! 
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 plants. 
This applies to the following species: 
Lophodermium pinastri....... on Pinus montana 
Phylosticta Pseudaceri........ - Iris germanica 
Phomavendolenrar. 22-72" - Alnus glutinosa 
Aposphaeria glomerata 
a olivaceum f et ea Sees nia 
Phomaltingens 22cm eee - 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. 
