The Botany of Iceland - 01.12.1930, Side 85

STL'DIES ON THE VEGETATION OF ICELAND
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principally or exclusively find such species as Koenigia islandica,
Sedum villosum, Juncus bufonius, biglumis and triglumis, Triglochin
palustre, Equisetum arvense, Cerastinm cœspitosum, Sagina nodosa,
Minuartia verna. On the small knolls the vegetation is connecled
and here we find the species Agrostis alba, Deschampsia alpina, the
Festuca spp., Armeria vulgaris, Rumex acetosa and several others,
principally such as are common to mo and jathar.
Helgi Jónsson was the first to describe the flag vegetation,
though without tlius naming it. His description of the vegetation on
the “clayey flats” which is referred to the “open vegetation of the low-
lands” corresponds to the description given above of the flag vege-
tation. In “Studier over 0st Islands Vegetation” 1895, p. 86, he says,
“they (i. e. the clayey flats) have most frequently a monotonous ve-
getation consisting of Sedum villosum, Koenigia islandica, Juncus
triglumis and other more casually growing plants. This vegetation
on clay varies not a little in composition; of the forms I have seen,
I note especially the following: a. The vegetation consists only of
Sedum villosum which occurs in a rather dense growth and gives a
fresh appearance to the clayey flats by its pretty flowers. b. The
vegetation consists only of Koenigia islandica wliich also occurs in
a rather dense growth but in this locality it is most frequently of
a red colour. c. The vegetation consists of Sedum villosum and
Koenigia islandica either in equal quantities or with now one, now
the other as the dominant. d. The vegetation consists of Juncus
triglumis as the dominant plant, besides scattered individuals of
Sedum villosum and Koenigia islandica, and Agrostis alba in scat-
tered tufts.”
“It should be noted that in many places a transition to the mo
vegetation is seen where most of the species of the mo occur
(Gramineae, Juncaceae) growing in scattered tufts with bare clay
between, it is merely a younger stage of the grass mo.”
In “Vegetationen paa Snæfellsnæs” 1900, pp. 43—44, we read:
“Plants characteristic of the clayey flats are Sedum villosum, Koenigia
islandica, Juncus alpinus and J. triglumis. The two first-mentioned
are most prominent and often occur in an astonishing quantity.
The most frequently occurring species are Agrostis alba, Aira alpina,
Sagina nodosa, Triglochin palustre, Epilobium palustre, Luzula spi-
cata, L. mnltiflora. In East Iceland this vegetation had quite the
same appearance. When these flats dry up in the summer, they
are often divided by cracks into many srnall polygonal areas,