304 THORODDSEN 



the lowlands may be mentioned, Carex rostrata, C. lagopina, C. saxa- 

 tilis, C. rigida, Eriophorum polystachyum, Luzula arcuata, Salix her- 

 bacea, Alsine biflora, Papaver nndicaale, Draba niualis, Arabis alpina, 

 A. petrcea, Saxifraga ccespitosa, S. oppositifolia , S. nivalis, Epilobinm 

 anagallidifolium, Gentiana niualis, Sibbaldia procumbens, Gnaphalinm 

 Norvegicum, G. supinum, and others. As already mentioned, many 

 of the most common plateau-species are distributed on rocky flats 

 throughout the country, both at high and at low levels ; for instance, 

 Silene maritima is as common along the coast as at the highest 

 levels in the interior wastes, as also Polygonum viuipamm, Cerasti- 

 am alpinum, Armeria maritima, Draba alpina, Oxyria digyna, and 

 several others. Therefore, speaking generally, it is not easy to dis- 

 tinguish the species of the rocky flats of the plateau from those of 

 the lowland. The main difference consists especially in the more 

 scattered growth of the individual plants and their partially stunted 

 appearance on the plateau; moreover, in the lowlands several spe- 

 cies are found intermixed with the above, often abundantly, which 

 rarely appear on the plateau, for example, Dryas octopetala. Fur- 

 ther, where the situation is favourable, very luxuriant patches may 

 occur on the rocky flat of the plateau, at any rate in the centre of 

 the island below r 600 700 metres. As we have already seen, the 

 altitude of the snow-line differs greatly in different districts, con- 

 sequently, the characteristics of the plateau vegetation are met with 

 at different altitudes in different parts of the island. In central Ice- 

 land the plateau-character often does not begin until at 600 800 

 metres, but on the northern peninsulas and headlands the plateau-vege- 

 tation often descends to an altitude of 300 metres, and in some places 

 even lower. On the lower-lying parts of the plateau, especially in 

 the neighbourhood of large glaciers, from which the melting snow 

 and ice has not sufficient outlets, there are often found groups of 

 lakes and extensive stretches of boggy and swampy land with a 

 luxuriant vegetation of mosses and sedges. Such swampy tracts 

 are found among other places on Tvidoegra (450 metres), in the neigh- 

 bourhood of Grimstungnaheidi (500 metres), Miklumyrar near H rep- 

 par (400500 metres), Eyjabakkar near Snsefell (650 metres), Fljots- 

 dalsheidi (400 500 metres), and Several other places. The vegeta- 

 tion of these plateau-bogs is as yet very little known. 



All the highest mountain summits and plateaus are covered with 

 snow and ice, but along the edge of the plateau and in a few places 

 upon the plateau itself there are several rather high mountain tops 



