The Botany of Iceland - 01.12.1945, Blaðsíða 116

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STEINDÖR STEINDÓRSSON
to the Icelandic lowland”, basing this statement on his own as well
as on other investigations. To avoid misunderstanding I wish to point
out here that this view is fully correct as regards the formation men-
tioned by Molholm Hansen under this name. As far as is known
to me, it has never been found in the highland. But the alpine forma-
tion described here is of quite a different nature and development and
should in no way be confounded with the lowland formation.
b. The Sand Vegétation.
Where the surface is covered with sand but not entirely devoid of
vegetation, the formation will develop which is here called the sand
vegetation. It is very scattered, and a ground vegetation is nowhere
found, both mösses and lichens being entirely absent. According to the
degree of moisture of the sand we may actually speak of two sand
formations. Where the sand is completely dry, every gust of wind will
cause it to drift, and such are the conditions in the greater part of the
extensive sand areas of the highland; hardly any vegetation is found on
these sand plains; some scattered individuals of Elymus arenarius,
Carex incurva, Silene maritima, and Arabis petraea may possibly be
seen, but often there is an interval of several hundred metres between
the individual plants. The wet sand is chiefly found along rivers and
brooks and very rarely covers large areas; such areas may sometimes
harbour a vegetation which is quite different from that of the areas
of blown sand. The greater number of the observations made here are
derived from these stretches of fluvial sand.
Helgi J ónsson (1900, pp. 45-47, and 1905, pp. 19-22) de-
scribes the sand vegetation, but it is exclusively the lowland sands or
in some cases marine sands. Moreover a great many of the areas called
sands by him are typical melur or gravel flats. This, for instance, ap-
plies to a great number of the sands of the southern part of the country
(1905). T h o r o d d s e n (1914, p. 331 ff) describes the sand vegeta-
tion of the highland as follows: “... the characteristic plant being
Elymus arenairius; but where it is very mobile, as e. g. on the plateau
in the neighbourhood of Fiskivötn and between Tungná and Skaftá,
no plant life can thrive on it. Where the sand becomes more stable,
or there is shelter, Elymus arenarius appears, often associated with
Festuca rubra v. arenaria; not until the sand becomes somewhat fixed do
other species appear, e. g. Juncus balticus, Carex incurva, Agrostis alba,
Festuca ovina, Silene maritima, Salix lanata, S. glauca.” T h o r o d d-