The Botany of Iceland - 01.12.1912, Side 196

182
H. JÓNSSON
with abundance of new shoots. The Rhodymenia-\egetation is never
really luxuriant in this place; it attains, however, to a greater
luxuriancy in spring and summer than during winter. Halosac-
cioneta occurred also here and there, but sparsely and not nearly
as abundantly as in spring and summer, but the same applies to
it, as to Rhodymenia, that it never grows really luxuriantly in this
place. There were noted in addition: — Monostroma fuscum, Py-
laiella littoralis (extremely sparsely) and Enteromorpha intestinalis f.
prolifera, also extremely sparsely. Lithodermeta occurred abun-
dantly and were well-developed, but the species was sterile. A
Sphacelarietum composed of Sphacelaria radicans was found here
and there. The plants were low in growth, sterile and withont hairs.
A Gigartinetum occurred here and there of about the usual extent.
Just below the limit of low-tide I gathered the uppermost
slragglers from the sublittoral zone. There Laminaria saccharina,
L. diyitata, L. hyperhorea and Alaria escutenta f., were growing. AIl
the Laminarias were slerile and tlie new laminæ had not begun to
grow. The frond of the Alaria was usually torn in pieces; in the
middle of the stipe there were old sporophylls. The uppermost
part of the stipe, just below the leaf-hase, was young and evidently
growing. Lowermost in tlie part that was growing, small projections
could be seen on the two sides, which were evidently the begin-
nings of new sporophjdls.
The following species were found thrown ashore: — Lami-
naria saccharina, L. digitata, L. hyperborea, Alaria esculenta f., Sac-
corrhiza dermatodea, Desmarestia aculeata, Odonthalia dentata, Pelro-
celis Hennedyi richly fruiting (on L. hyperborea), Rhodochorton Rothii
(on L. hyperborea), Delesseria sanguinea with the small tetraspore-
bearing fronds, and Ptitota plumosa with tetraspores.
For tlie further understanding of the winter-life of the algæ it
may be mentioned that the winter of 1911—1912 was unusually
mild at Reykjavík.