31 



sea, where there are good biological conditions above the fog 

 from the sea and the cold from the icebergs \ was covered by 

 Hippuris and water-mosses. Krdcse (1906 p. 224) states "sets 

 ripe fruit", Angmagsalik ca. 66° N. L., East Greenland. 



Vegetative propagation seems predominant here even to 

 a greater degree than in temperate regions. Whether it can 

 proceed here, in addition to by running shoots in the bottom, 

 as Sernander (1901 p. 175) describes, also by means of loose 

 plagiotropic shoots on which are placed orlhotropic ones with 

 a kind of hibernaculum, and by means of others with short 

 internodes furnished with compressed leaves, which are formed 

 in the axils of the leaves, or how' the spreading from water to 

 water proceeds, is not shown by the material, and just as little 

 the mode of passing the winter. Jonsson (1895 p. 290) on 

 January 10th found the large and small pieces of ice lying on 

 the bank of a large channel at Vallanes, Iceland, densely covered 

 on the downward side with Hippuris and Equisetiim limosum, 

 which were still living and which had earlier been carried away 

 by the ice. At Angmasalik 65° — 66° N. L. "the air shoots 

 begin to appear early in June" (Krucse 1906 p. 224). 



Hippuris belongs just as little as Myriophyllum and Calli- 

 triche to the water-plants, whose resistance to the cold has been 

 investigated by Lidforss (1907 p. 47). 



It is unknown, how far the rather variable arctic form — or 

 more correctly speaking Greenland form, to judge from the com- 

 position of the material — called for practical reasons f. litoralis 

 Lindberg, is constant or if it is which is most probable only a 

 reduced H. vulgaris, which certainly flowers — even a specimen of 

 only 7 — 8 cm in height from Angisek, Kitsigsut Islands 59°58' N.L. 

 KoLDERüp KosENviNGE (1896 p. 65) — bul remains for a long 

 time at an early stage of development in vegetative regards. 

 Often the short, broad leaf-form is retained very long, and on the 

 whole the plant does not attain all the developmental stages, the 

 ' According to verbal communication from Dr. N. Hart/. 



