946 



the existence of large swamps. Such swamps as there are occur on 

 the margins of some of the lakes or in the numerous small pools 

 present all over the lower country, some being natural, while others 

 are the result of human agency, — turf-cutting, etc. 



The vegetation on swampy lake-margins differs considerably 

 from that of the pools, hence my division of the Færoese swamp 

 formation into two associations : 



a. Heleocharis association. 



/i. Menyanthes-Polygonifolius association. 



Heleocharis association. This forms the transition from 

 the v^^ater-vegetation to that of the moors near a few Færoese lakes. 

 The association — very familiar to us round the smaller lakes of 

 the heath-regions of Jutland and other parts of Denmark — is found 

 in its typical form at Vaag-Vatn on Sydero, with Heleocharis pa- 

 lustris, Eqiiisetiim fliwiatile, E. paliistre, Carex salina and Ranun- 

 cnlus flammula. A similar vegetation made up of Heleocharis pa- 

 histris, Iris pseudacorns, Carex salina, Menyanthes, Myosotis pahistris 

 strignlosa and Galium palnstre was also observed round the lakes 

 at Eide on Ostero. At several piaces on the margin of Sandsvatn 

 on Sando we also observed patches of Heleocharis palustris, Carex 

 salina and Polygonum amphibium natans. Traces were also found 

 in other piaces (e. g. Example 5, p. 941); one or two of the species 

 already named forming small patches. 



The only characteristic species are Heleocharis pahistris, Equise- 

 tiim fluviatile and Carex salina, all three being species with vigorous, 

 horizontal, subterrean rhizomes ^. 



Menyanthes-Polygonifolius association. The association 

 to which I give this name is of more frcquent occurrence than the 

 last, but not so easy to define. The principal piants are Menyanthes 

 and Potamogeton polygonifolins. The latter species appears in all 

 piaces where there is a bare substratum of muddy peat, which is 

 permanently, or at least occasionally at certain periods, saturated 

 with water. Here Potamogeton polygonifolins forms a more or less 

 dense growth, which is a forerunner of the true bog and moor 

 vegetation. 



Menyanthes occurs with the Potamogeton, or it may entirely re- 

 place it in many pools, especially the larger ones. Several other 

 piants may also appear, e. g. Myosotis repens (only on Sydero), 



^ The occurrence here of Carex salina out of its natural habitat in the salt- 

 marsh, is due to the faet that the few localities for swamp are all near the ocean. 



