STUDIES ON THE VEGETATION OF ICELAND 99 
Silene acaulis, Luzula arcuata, Arabis petræa, Aira alpina, Oxyria 
digyna, Salix herbacea, and Saxifraga rivularis. “At higher levels 
only some few individuals of Salix herbacea, Sibbaldia procumbens, 
and Aira alpina were met with.” 
“In the lower fell-field the phanerogams play a much more pro- 
minent part”. The most frequent plants here are: Salix herbacea, 
Saxifraga rivularis, Sibbaldia procumbens, Oxyria digyna, Ranunculus 
glacialis, Pedicularis flammea, Luzula arcuata, and Epilobium ana- 
gallidifolium. 
“The following occur frequently: Silene acaulis, Carex rigida, 
Polygonum viviparum, Empetrum nigrum, Loiseleuria procumbens, 
Cassiope hypnoides, Armeria maritima, Arabis petra, Veronica alpina, 
Thalictrum alpinum, Luzula spicata, Juncus trifidus, Saxifraga cespi- 
tosa, Alchemilla alpina, Cerastium alpinum, Aira alpina, Thymus Ser- 
pyllum, Saxifraga oppositifolia, Gnaphalium supinum, Cerastium tri- 
gynum, Poa glauca.” 
“The less frequent are: Betula nana, Dryas octopetala, Papaver 
radicatum, Salix glauca, Trisetum subspicatum, Poa alpina, Pyrola 
minor, Saxifraga nivalis, S. hypnoides, Galium silvestre, Ranunculus 
acer, Cystopteris fragilis. Of rarer occurrence are: Taraxacum levi- 
gatum, Rumex acetosa, Rhodiola rosea, Carex lagopina, Potentilla 
verna, Luzula multiflora, Festuca ovina.” 
III. The Anthelia crust. “On gravelly, clayey, or stony soil, 
in the mountains, at an altitude of 300—700 m., increasing with 
the height, a grey crust, dispersed in patches, is very often met 
with. It is formed exclusively of Anthelia nivalis. Interspersed 
with it I sometimes found Grimmia hypnoides, G. ericoides and Salix 
herbacea. This Anthelietum often borders on the Salix herbacea 
depressions. Transitional forms between the Anthelia and the Salix 
herbacea vegetation are occasionally found.” 
IV. The Salix herbacea and Sibbaldia vegetation. 
“... occupies the aforementioned depressions where the clayey strata 
cover the subsoil. The main dispersal of this vegetation lies be- 
tween 300 and 600 m. above sea level. In the lower part there is 
often a strong admixture of the elements of the heather moor, and 
at an altitude of over 600 m. it passes into the moss vegetation. 
An undergrowth formed of mosses is nearly always present.” “Very 
often it is formed of Grimmia hypnoides and occasionally of An- 
thelia nivalis.’ “Not a few of the phanerogams of the fell-field are 
interspersed in the Salix and Sibbaldia patches. As far as I could 
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