406 And». Llndac.kh 



the (lislricl lu'ar Lakset'lv, found on .Iiuu' If), 1907; il measures 2.32 

 metres in length and 1.45 metre in breadth and is almost withered 

 to windward (NW.) and in the middle, but has a vigorous, though 

 wind-alTected border, to leeward. Hut these tufts keep to the ground 

 and thereby stand in contrast with the curious '*column"-forms in 

 which Potentilla pulchella occurs both on Ymers Nunatak and in 

 those places upon the gravel-banks near Lille Sncnæs which are most 

 exposed to the wind. The individuals from Ymers Nunatak appeared 

 to have struggled against the sand-drift and thereby to have attained 

 the compact, high tuft-form in order that they may be able to 

 keep "above water." But the individuals of this form which I 

 myself collected, stood quite isolated over the field and showed a 

 much wind-affected and leafless base. The conditions there did not 

 in any way permit the sand to gather around these "columns." 

 Lesqiierella and a Draha sp. from the same exposed posts have the 

 same form (cf. List, p. 23 and PI. V). It appears to me, judging 

 from my observations in the field, that the form hiimilis (Lange) of 

 P. pulchella prefers the weather-side to the lee-side tliough it is found 

 also in that situation in company with P. nivea. But on the lee- 

 side the tufts appear far fresher and have always a broad base. 



P. pulchella f. elatior (Lange) is often found upon high sloping 

 river-banks consisting of loose sand mixed with clay; but in con- 

 tradistinction to the xerophilous f. humilis with its densely hairy, 

 silvery white leaves f. elatior has slightly hairy leaves which are 

 green upon the upper surface. In such places it must often stretch 

 far and wide for food; I have found it with roots which measured 

 1,15 metre and to a great extent were lying so high that a portion 

 of them lay bare. 



It seems to me that Salix also must allow its form to be deter- 

 mined by such external factors as the wind. The illustration (Fig. 17) 

 shows the largest "copse" I have seen; it occurred upon a stony slope 

 above the station in Pustervig. Salix often adopts a curious form 

 according to the adverse circumstances it meets with, but it always 

 keeps close to the ground. The most beautiful branches I have 

 seen I found upon Harefjeld on June 24, 1907. They were two 

 13-years-old branches, d^ and Ç, measuring respectively 48 and 57 cm. 

 in length. The male branch was somewhat thicker than the female 

 which had a year's-shoot measuring 9 cm. and bore a leaf the blade 

 of which measured 51 X 30 mm. The leaves were slightly hairy and 

 the branches smooth. The exposition was as favourable as possible 

 as regards shelter, snow-covering and sun. The male catkins expand 

 first, and upon level ground always earliest in that part of the 

 catkin which faces south. 



