The Botany of Iceland - 01.12.1930, Blaðsíða 40

30
H. M0LHOLM HANSEN
of the country E., N., N. W., S. W., and S. Iceland. The designation
algeng, hjer & hvar, or sjaldgæf after each species denotes whether
the species is common, scattered or rare. For each of the 5 parts of
the country have been added up the species of the respective groups
1) wrhich are absent, 2) wdiich are scattered to rare or 3) w’hich are
common within the area. The investigation has been carried out for
the flora as a whole, for the main groups, A and E, and for the sub-
groups under these twro groups, and the result expressed in percent of
tlie species number of the group in question has been given in table 6.
The means for all parts of the country are given below in the table.
The A group has more common species, less rare or absent species
than the E group; while on an average 15,4 p. c. of the species of the
A group are absent in each part of the country, the same figure
for the E group is 22,9 p. c. For the commonly occurring species the
proportion of A to E is as 54.7 to 38.8.
If next we turn to the subgroups, the table showrs that A 2 has
the greatest number of common species, while A 3 and especially
A 1 show a smaller number. Of tlie E subgroups, E 4 has the
greatest number of common species, 62,8 p. c., E 1 the smallest number,
8,6 p. c. E 3 and E 2 occupy an intennediate position with 54,0 p. c.
and 32.5 p. c. respectively of common species. The numerical values
for the rarer and absent species entirely confirm the sequence. In
addition the table shows the quantitative conditions of the flora
and species groups in the 5 Icelandic areas. The A group occurs
most frequently to the east and north, the E group to the south
and south-west. In the A group tliis is due especially to A 2, in
the E group, to E 2 and E 1.
Aided by the above-mentioned tables we can now give the
following description of the distribulion of the Icelandic species
groups in norlhern Europe and tlie arctic regions.
The E group comprises species of common occurrence in Cen-
tral Europe. The species liave their main distribution to the south
of or belowr the forest limit, the 20 p. c. Ch biochore. The various
species, however, transcend this limit in varying degree in conse-
quence of which the following 4 subgroups may be distinguished.
E 1 requires the greatest amount of heat. In England, Denmark,
northern Germany, and soutliern Scandinavia the E 1 species are
of common occurrence. In Finland they only occur in the most
southerly part, in northern Scandinavia only or principallj' on shel-