548 A. HESSELBO 



A. The Bryophyte Vegetation of Pure Water. 



a. The Bryophyte Vegetation of Running Water and of 

 Lakes. 



b. The Bryophyte Vegetation of Inundated Gravelly Soil 

 (slightly inclined ground and banks of streams). 



c. The Bryophyte Vegetation on Muddy Soil near Springs (Dv). 



B. The Bryophyte Vegetation of Boggy Soil 1 . 



C. The Bryophyte Vegetation of Damp Sandy Soil. 



D. The Bryophyte Vegetation near Hot Springs. 



The Bryophyte Vegetation of Running Water and of Lakes. 



The Bryophyte Vegetation of Lakes is extremely scanty, 

 and often entirely absent. Along the shores of shallow lakes the 

 surrounding swamp-vegetation may extend right into the water, 

 especially species such as Hypnum giganteum, H. exanmilatam and 

 //. scorpioides , while rocky shores are usually quite bare of sub- 

 merged Bryophyte vegetation or bear, here and there, one or other 

 of the species growing in streams, such as Fontinalis antipyretica or 

 a //ypnum-species. How far Bryophyta (for instance, Fontinalis) 

 may occur in deeper water has not been investigated. 



Glacier- rivers, on account of their torrential current and 

 changeable course, as well as of the low temperature of their clay- 

 containing water, are entirely devoid both of Bryophyte vegetation 

 and of higher plants. 



Brooks and Rivers. Where the bottom consists of loose 

 gravel and smaller stones which are kept by the water in constant 

 motion, Bryophyte vegetation is entirely absent. But if the bottom 

 is of firm rock or larger stones it is, as a rule, covered with ex- 

 tensive moss-carpets which usually consist of Hypnum ochraceum 

 or Fontinalis antipyretica, which may, either separately or together, 

 cover large areas of the bottom. In very strong currents H. ochra- 

 ceum forms the highly elongated and often thread-like var. filiforme 

 which, together with Rhynchostegium rnsci forme var. atlanticum, is 

 a characteristic species of torrential rivers on much inclined ground. 

 H. ochraceum var. filiforme is found especially in larger streams, 

 where it is then the only species occurring, while Rhynchostegium 



1 In this paper no distinction has been made between swampy soil, marshy 

 soil and boggy soil, the term "boggy'' includes all three kinds of soil. The Danish 

 term in all three cases is "sumpet". 



