The Botany of Iceland - 01.12.1945, Side 59

THE VEGETATION OF CENTRAL ICELAND
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glacialis, also, is very common; in addition there occur species of the
genera Bryum and Amblystegium and other genera. Scattered individ-
uals of various phanerogams occur in the dense and moist mossy carpet.
On account of the yellowish-green colour of the mosses the patches of
dý are often visible from a great distance, especially on the mountain
sides, where they are surrounded by the fell-field poor in vegetation.
In the mýri or flói formations the boundaries are more indistinct. The
dý vegetation has been described by several earlier authors, thus by
Jónsson (1895, pp. 73-74, etc.), Hesselbo (1918, pp. 55i-555)>
who gives a precise description of it, especially of its moss vegetation,
and Thoroddsen (1914, p. 321), who summarises the earlier de-
scriptions into a brief survey. In the highland regions investigated by
me the actual dý formation is rather rare, whereas a rim of Philonotis
along the brooks is commonly met with, especially in Fagridalur, where
the mountain sides over vast stretches are carved by brooklets lined
with light-green Philonotis cushions often entirely devoid of phan-
erogamous vegetation, or with a few scattered individuals from the
adjacent formations. Similar conditions are found along the brooks
in Hvannalindir. Where the banks are low, belts of Philonotis often oc-
cur along them, but these belts contain a great many phanerogams,
Archangelica, in particular, is often very conspicuous (cf. Anderson
& Falk 1935, pp. 411-412, Zone D). Altogether the vegetation of
Hvannalindir is mixed with Philonotis in several places where the soil
is penetrated by the spring water. Similar rims of Philonotis were found
along brooks in Þorlákslindir also; a moss sample from this locality
contained the species Philonotis fontana and Amblystegium ochraceum.
In the dý vegetation investigated by me in the highland I noted the
following species:
Cerastium trigynum
Deschampsia alpina
Agrostis alba
Eriophorum Scheuchzeri
Poa alpina
Oxyria digyna
Equisetum arvense
Saxifraga stellaris
„ rivularis
And in the marginal zone of the dý vegetation:
Polygonum viviparum Salix glauca
Carex rostrata Carex rigida
As a typical example of the vegetation around a spring I subjoin
a list from Viðidalur in Lón at c. 700 m altitude above the sea: