The Botany of Iceland - 01.12.1912, Síða 80

66
H. JÓNSSON
element in E. Iceland and the boreal element in S. and SW. Iceland
are much more sharply defined; and this is natural, as the species
assumed to be common are omitted. Even if we consider only the
known distribution of the species, in its entirety (see Table 1). the
distribution of tlie here-mentioned 76 species will still be the most
essential reason for the floristic difference between the parts of the
coast.
The species assumed to be common are 124 (see above). Of
these none are arctic, 25 belong to the suharctic group I, 46 to the
subarctic group II, 26 are boreal-arctic, 26 cold-boreal, and one
(Phormidium autumale) is warm-boreal. Of the 76 not-common
species, 11 are arctic, 6 belong to the subarctic group I, 4 to the
subarctic group II, one (Ahnfeltia plicata) is boreal-arctic, 43 are
cold-boreal and 11 warm-boreal. If we add logether the numbers
representing the species of the corresponding groups as regards the
124 species assumed to be common and the 76 not-common species
(Table 5), and compare witlr Table 3, we find that the species are
more numerous in each district, but that the percentages are almost
the same.
If the groups are divided in two parts, A and B (see above) so
tliat A includes the arctic and subarctic groups, and B the three
other groups, the following figures are obtained (see Table 4): —
E. Icel. N. Icel. NW. lcel. SW. Icel. S. Icel.
A ... . 50 (63 %) 47 (54 %) 42 (58 %) 48 (42 %) 25 (30 %)
B . ... 30(37 %) 40 (46 %) 31(42%) 67 (58 %) 59 (70%)
The arctic group is jioorly represented in all the districts of
the coast (see Table 4) and therefore the flgures mentioned above
under A apply chiefly to the subarctic group; the floral districts of
E. Iceland, N. Iceland and NW. Iceland are thus subarctic. E. Ice-
land is subarctic. to a greater extent than N. and NW. Iceland. SW.
Iceland is a boreal floral district with a very considerable subarctic
element, and thus resembles the coasts of Iceland taken as a whole
(see above). S. Iceland is a boreal district with a slightly subarctic
element.
Floristic Boundaries.
The mixed character of the flora in N. and NW. Iceland has
been alluded to several times in the foregoing pages, and is clearlv
seen from the tables given, as, for example, Tables 2 and 5. Here,