The Botany of Iceland - 01.12.1914, Blaðsíða 137

PHYSICAL GEOGRAPHY
321
Springs (kaldavermsl, dy1) are very comnion in Iceland, and
are found in almost every valley below the mountain-sides or appear
in rows upon the ledges of the basalt-layers. The peculiar vegeta-
tion connec.ted with these streams is widely distrihuted below the
mountain-sides and ol'ten occurs in the midst of other formations or
high up on the mountain-sides in narrow zones in places where
other vegetation is wanting. This vegetation is characterized espe-
cially by the fresh bright-green colour of the mosses; Philonotis fon-
tnna is everywhere the dominant plant, but many other species of
moss also occur, especially Pohtia atbicans var. glacialis, and various
species of Brgnm, Amblgstegium, and several other genera. Several
phanerogams occur among the mosses, the most cominon are Epi-
lobium alsinefolium, E. Hornemanni, Cerastium triggnum, Montia ri-
vularis, Saxifraga stellaris, and Catabrosa aquatica, sometimes asso-
ciated with Ranunculus hgperboreus and Cattha patustris, Marchantia
polgmorpha, etc. As this spring-vegetation usually occurs close to
bogs and swampy tracts, there are ofteii transitions to bog- and
swamp-vegetation.
Vegetation around Hot Springs. Peculiar to Iceland is the
characteristic vegetation near hot springs. The heat of the soil and
the hot water create exceptionally favourable conditions for plant-life,
so that species which otherwise do not grow in Iceland can thrive
here, and species from South Iceland which do not otherwise grow
in North Iceland also occur liere near hot springs. It is to be regretted
that the vegetation connected with these springs has been more
closely investigated in a few places only2. It is especially the rich
algal ílora, which for instance is of great importance as regards the
separation of silica from the hot water, which requires investigation.
The vegetation around the hot alkaline springs is usually very luxu-
riant and may extend over fairly large areas, because the aqueous
vapour íloats above the surroundings and descends as a continuous,
drizzling rain of tepid water. The plant-associations may differ some-
what according to local conditions, as to whether the surroundings
are damp or dry, gravelly or rieh in humus. Where the surround-
ings of the springs consists of a hard grass-bottom, the followdng
1 In Iceland the word “dy” is also applied to small pools in swampy tracts.
2 Plant-life near the hot springs has been investigated especially by C. Osten-
feld, Bot. Tidsskr., vol. 22, 1899, pp. 299—245; byChr. Grönlund: Karakteristik
af Plantevæxten paa Island, pp. 33—35 and by Japetus Steenstrup and F. M.
Liebmann, Forhandl. v. d. skandin. Naturforskeres 2. Mode 1840, Kobenhavn, 1841,
pp. 336-340.