556 A. HESSELBO 



In "Die Moose des Sarekgebietes" (1910, p. 248) C.Jensen 

 classifies the bog vegetation in four formations: The Willow bog, 

 the Sedge bog, the Moss bog and the Peat bog. This classification 

 cannot be entirely adopted as regards Iceland. Willow bogs proper 

 (willow coppices in boggy soil) do not appear to be developed there. 

 True, scattered individuals or small groups of Salix [S. lanata, S. 

 phylicifolia and S. glauca) are often found in the sedge bogs, espe- 

 cially in NW. Iceland, but the moss vegetation there does not 

 differ in any respect from that of the surrounding sedge bog. 



The vegetation of boggy soil is composed mainly of mosses 

 and sedges, greatly varying in abundance. Sometimes the sedges 

 are the dominant piants, and then the moss carpet is less conspicuous 

 at the bottom, among the Carex and Eriophorum spp.; sometimes 

 there is a continuous moss-carpet in which the higher piants grow 

 scattered, and then the one formation may be termed a sedge bog, 

 and the other a moss bog, which, however, does not correspond 

 with Helgi Jonsson 's definition of a moss bog, but appears to 

 agree with Warming's description (1887, p. 132). They are the 

 same mosses which occur in the same manner in both formations, 

 and all possible transitions are found between these. 



Helgi Jonsson (1900, p. 20: 1905, p. 9) classifies the bog 

 vegetation into Star-grass bogs and Moss bogs. The latter, which 

 include the vegetation along streams, on inundated ground and near 

 springs (Dy), and also some of the moss bogs in Warmings defi- 

 nition, have been treated in the preceding section. The star-grass 

 bogs are again divided into "Mjrar" and "Floar". In the M\ri the 

 ground water stands on a level with the surface, the soil contains 

 acid humus and is so closely interwoven with rhizomes and roots 

 that it bears one like a carpet. In the Floi the ground water 

 stands above the surface, the soil is muddy and produces a more 

 scattered vegetation of Carex and Eriophorum tufts. As it is chiefly 

 the height of the ground water which determines whether a M^ri 

 or a Floi is developed, and the Floi is formed by the filling up of 

 a shallow lake, there occur all transitions between lake and Floi, 

 and through further development, between Floi and Mjri. 



The Floi is poor in mosses. The soft muddy soil is not 

 favourable to their growth, and it is only as an exception that 

 some of the species are found which grow along the banks of 

 lakes, but often the moss-covering is entirely absent. Hypniim 

 scorpioides and H. giganteum are the most frequent species which 



