The Botany of Iceland - 01.12.1912, Side 185

MARINE ALGAL VEGETATION
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Sweden (Kylin, 45) the hairs are cast in June, but (j'oung) hair-
bearing individuals may, liowever, be met witli in July.
Pohjsiphonia urceolata has hair-leaves in the spring, summer
and beginning of autumn, but individuals without hairs are found
side by side with hair-bearing ones from May to August. In De-
cember only hairless individuals have been observed at Reykjavík,
and in January—February only hairless plants have been collected
in N. Iceland.
Rhodomela hjcopodioides has been collected with hair-leaves in
March—July, and hairless in June—August in SW. Iceland; with
hair-leaves in April—December, and hairless in July—August in N.
Iceland; with hair-leaves in June—July and hairless in May—July
in E. Iceland. In the autumn this species had cast off its leaves
and branches in SW. Iceland.
In addition to this, the following instances of the occurrenee
of young shoots may be mentioned: —
Odonthalia dentata. The young shoots in this species are readily
recognized by their paler red colour. Material from January—
February bears young shoots. The latter are easily recognizable in
January, and have probably begun to grow out in December. The
young shoots then increase in size, and the colour becomes gradu-
ally darker month by month. In material collected in June—July
the length of the year’s shoot may even then be determined in
some of the individuals, but I believe, however, that it is in July
that the shoot is almost full-grown.
Polijsiphonia fastigiata has young slioots in December at Reykjavík.
Odontlialia sbows distinctly the period of development of the
vegetative shoots in the sublittoral zone, and I presume it may be
taken for granted that the other sublittoral species do not ditfer
very much from it as regards this point.
In Greenland the formation of the new shoots begins in Feb-
ruary—March (Rosenvinge, 63, p. 239), and tlie growth is con-
tinued until August or during the whole summer.
In the Færöes the new shoots begin to appear in the latter part
of autumn (Börgesen, 12, p. 828).
From Spitzbergen (Kjellman, 36) some sublittoral species are
known which form new shoots during the winter, as for instance,
Delesseria sinuosa in January, and Rhodymenia palmata from No-
vember to May.