The Botany of Iceland - 01.12.1912, Page 184

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H.JÓNSSON
lamina takes place in February—Marcli. In April individuals with
large, new laniinæ, with the old laminæ or portions of Ihem still
attached, are frequently found at Reykjavík, but the majority of the
Laminaria individuals have renewed their Iaminæ by that time. A
few individuals are however met with until June in SW. Iceland in
the act of lamina-renewal. With regard to some of the most common
species the following may be noted: —
Laminaria saccharina in SW. Iceland (1897) was frequently found
in the lamina-renewal stage in April, while some individuals were
renewing their laminæ in May. Laminaria digitata: some individuals
were renewing their laminæ in April and until June in SW. Iceland
(1897). Laminaria hyperborea in SW. Iceland (1897), some were re-
newing their laminæ in May—June.
L. hyperborea was found renewing its laminæ in Julv on the
nortli coast of Iceland. This was observed only once, therefore it
cannot be concluded from this that the lamina-renewal stage com-
mences later or lasts longer on the north coast than in SW. Iceland.
In the Færöes (Börgesen, 11 and 12) the lamina-renewal stage
occurs at the same time as in SW. Iceland.
On the west coast of Sweden the renewal of the lamina takes
place during winter (Kylin, 45) and in Laminaria saccharina and
L. digitata the young leaf, in December, is a quarler the size of the
old one; in April it is only exceptionally that individuals are found
with a portion of the old lamina attached. The renewal of the lamina
in L. hyperborea takes place later, and in April the new lamina is a
quarter the size of the old one, and in the beginning of July a
portion of the old Iamina is still present.
In connection with the lamina-casting species the following may
be mentioned: —
Desmarestia aculeata has been collected bearing the brown, as-
similatory hairs in March—May in SW. Iceland, in May in NW.
Iceland, in June in E. Iceland, and in July in N. Iceland. This
appears to indicate that the hair-bearing stage occurs later on the
north and east coasts, or that it lasts longer. The species behaves
in the same manner in Greenland (Rosenvinge, 61. p. 857) where
the hairs are cast off, at the latest, in June in South Greenland,
while hair-bearing individuals are found in July and August in
Nortli Greenland. In the Færöes it has been observed with hairs
upon it in May—June (Börgesen, 13, p. 445), but hair-bearing
jndividuals were, however, rare in June. On the west coast of