Vegetation of the Island of Gothland. 261 
temperature (6'4 n C) does not seem to differ very much from that 
of the mainland at Lund, but probably the winters are milder; the 
rainfall (472 mm.) is somewhat less than at Lund. In spite of the 
somewhat similar climatic conditions, the Gothland flora presents 
some striking differences from that of the mainland. This is 
probably due to the geological structure of the island. 
The underlying rock of which the island is composed, is almost 
entirely Silurian limestone which is very welt developed and forms 
nearly horizontal beds. There are steep cliffs on the western 
coast-line but the whole of the interior is very flat and forms a 
plateau about 40 metres above sea level. The underlying rock is 
generally covered with a considerable thickness of glacial drift of 
varying composition, but chiefly of a sandy and gravelly nature, 
though the soil is usually calcareous. In many places the drift is 
now absent and the limestone appears at the surface and bears a 
“ limestone pavement ” flora. Much of the cultivated land in the 
island has been derived from what must have formerly been 
extensive marshes or lakes. These have been drained and the 
original lakes have either disappeared or have been reduced to the 
size of ponds. The land covered by the sandy drift was in most 
places occupied by pine forest and some of this country also has 
been reclaimed by man. 
Floristics. 
Dr. Johansson has given a careful analysis of the flora 
in his paper. He has distinguished about 1008 species of flowering 
plants and ferns, but of this number about 100 are species 
of the genus Hieracium. A few of the plants do not occur elsewhere 
in Sweden, though the flora in general is very closely related to the 
flora of the island of Oland, nearer the Swedish coast, and also to 
the flora of the Russian provinces on the other side of the Baltic, 
where similar Silurian rocks occur. Many of the plants, however 
especially those of the pine forests, occur also in localities on the 
mainland extending northwards for a considerable distance. 
General Ecological Divisions. 
Johansson has distinguished the following plant communities 
(vaxtsamhallen):— 
1. Sea plants. 
2. (a) Fresh-water plants. 
(b) Water-loving swamp plants. 
3. (a) Marsh plants (proper). 
(b) Limestone bog plants. 
