1898-1902. No. 2.] VASCULAR PLANTS OF ELLESMERELAND. 61 



where it was not found when an excursion was made, and only in the 

 most utterly poor limestone districts it was not immediately found after 

 walking only a few paces on shore. It grows also in nearly every kind 

 of locality, and even if it absent from the most swampy bottom, it can 

 still be found on the top of the higher knolls, where it is a little drier. 



It is very variable, both in manner of growing and shoot-system of 

 the individual, as well as in size and colour of the flowers. Andersson 

 & Hesselman, 1. c, p. 25—26, have distinguished two forms, that differ 

 in their mode of growth, f. piilvinata and f. reptans. They could also 

 be distinguished in Ellesmereland, but I have not found them so sharply 

 defined as, according to these authors, they must be in Spitsbergen. 

 The same distribution of the forms, which is mentioned from Van Keu- 

 len Bay, I have also observed in many places, and I think it is easily 

 explained. The origin of the pulvinate form in depressions, is caused 

 directly by the influence of outward conditions. S. oppositifolia, in 

 fact, is not the only plant which grows thus in such locahties. Cera- 

 stium alpinum, for instance, shows there an equal tendency to form 

 dense tufts, and another densely pulvinate plant from similar localities 

 is Alsine Rossii. Most probably this stands in connection with the fact, 

 that such localites, the even clay plains, as well as the depressions in 

 the more undulated fields of the same kind, will, during the melting of 

 the snow, all be inundated by a shallow layer of clay-laden water, which 

 runs very slowly and deposits rather considerable quantities of loam. 

 If S. oppositifolia should grow here as usual, prostrate and spread 

 like a mat, it would every year, be covered by a layer of clay, may be 

 thin, which would impede its early development or even kill it. By 

 growing in tufts which reach over the water, it avoids this, but then 

 the forming of tufts naturally necessitates another kind of ramification. The 

 cause for the appearance, also mentioned by the same authors, of large 

 mats in the river beds, where also the bottom is rather httle stabile, 

 may perhaps be sought therein, that a high tuft would too easily catch 

 the gravel transported by the fast-running wather and thus be buried. 

 Here the plants become totally submersed during the flood and then 

 probably, the matlike growth is less apt to hold fast the coarse mate- 

 rial which is here carried along. Very often, however, the mats of 

 S. oppositifolia and other plants growing in such places, are totally 

 covered and killed, or also washed loose and swept away. 



S. oppositifolia is called the most arctic of all higher plants and 

 indeed it is found so far north as man has reached on dry ground. 

 It is also one of the first to show signs of fife in spring time and 



