PHYSICAL GEOGRAPHY 321 



Springs (kaldavermsl, dy 1 ) are very common in Iceland, and 

 are found in almost every valley below the mountain-sides or appear 

 in rows upon the ledges of the basalt-layers. The peculiar vegeta- 

 tion connected with these streams is widely distributed below 7 the 

 mountain-sides and often occurs in the midst of other formations or 

 high up on the mountain-sides in narrow zones in places where 

 other vegetation is wanting. This vegetation is characterized espe- 

 cially by the fresh bright-green colour of the mosses; Philonotis f'on- 

 lana is everywhere the dominant plant, but many other species of 

 moss also occur, especially Pohlia albicaus var. glacialis, and various 

 species of Brynm, Amblystegium, and several other genera. Several 

 phanerogams occur among the mosses, the most common are Epi- 

 lobium alsine folium, E. Hornemanni, Cerastium trigynum, Montia ri- 

 vularis, Saxifraga stellaris, and Catabrosa aquatica, sometimes asso- 

 ciated with Ranunculus hyperboreus and Caltha palustris, Marchantia 

 polymorpha, etc. As this spring-vegetation usually occurs close to 

 bogs and swampy tracts, there are often transitions to bog- and 

 swamp-vegetation. 



Vegetation around Hot Springs. Peculiar to Iceland is the 

 characteristic vegetation near hot springs. The heat of the soil and 

 the hot water create exceptionally favourable conditions for plant-life, 

 so that species which otherwise do not grow r in Iceland can thrive 

 here, and species from South Iceland which do not otherwise grow 

 in North Iceland also occur here near hot springs. It is to be regretted 

 that the vegetation connected with these springs has been more 

 closely investigated in a few places only 2 . It is especially the rich 

 algal flora, which for instance is of great importance as regards the 

 separation of silica from the hot water, which requires investigation. 

 The vegetation around the hot alkaline springs is usually very luxu- 

 riant and may extend over fairly large areas, because the aqueous 

 vapour floats above the surroundings and descends as a continuous, 

 drizzling rain of tepid water. The plant-associations may differ some- 

 what according to local conditions, as to whether the surroundings 

 are damp or dry, gravelly or rich in humus. Where the surround- 

 ings of the springs consists of a hard grass-bottom , the following 



1 In Iceland the word "dy" is also applied to small pools in swampy tracts. 



2 Plant-life near the hot springs has been investigated especially by C. Osten- 

 feld, Bot. Tidsskr., vol.22. 1899, pp. 299245; by Chr. Gronlund: Karakteristik 

 af Plantevsexten paa Island, pp. 3335 and by Japetus Steenstrup and F. M. 

 Liebmann, Forhandl. v. d. skandin. Natnrforskeres 2. Mode 1840. Kebenhavn, 1841, 

 pp. 336-340. 



