Flowering Piants and Fems from North-Western Greenland. 17 



68. Potentilla nivea L., var. pinnatifida Lehm. 



Seems to be rare in the area, but is often very difficult to separate 

 from the following species, which perhaps is a hybridogenous form 

 coming from the cross between P. nivea and P. piilchella. 



Ingl. L.: Advance Bay (26.-27. VI, flow.). 



69. Potentilla Pedersenii (Rydb.) Rydb., North American Flora 

 (1908); cfr. Ostenfeld, in Medd. Grønl. LXIV, pp. 182—187. 



Wasli. L.: Limestone rocks near Cape Calhoun (8. VI, sterile; Identification 

 doubtful); Putlersuak (L. K., 13. VIII, in fruit). 



Ingl. L.: Advance Bay, together with the foregoing species (26. — 27. VI, 

 flow.); Marshall Bay (2. VII, in fuU flow.); W. of Eensselaer Bay, Anoretuk (20. 

 VII, well developed specimens in full flow.). 



Murch. S.: Mac Cormick Bay, river-bed (7. IX, in flow. and fruit). 



Together with the specimens from the last mentioned locality are 

 some specimens of vigorous growth and in fruit (rather few achenes 

 developed); their tomentum is much less dense than in P. nivea and 

 P. Pedersenii^ and I consider them to be the hybrid P. emarginata x 

 Pedersenii vel nivea. 



70. Potentilla pulchella R. Br. 



Wash. L.: Putlersuak (L. K., 13. VIII, flow. over). 



71. Potentilla Vahliana Lehm. 



Murch. S.: S. of the inhabited place at Piteravik (10. XI, winter stage). 



Salicaceæ. 

 72. Salix arctica PalL, emend. 



Common in bogs, around tårns and in niany other habitats of the 

 area. 



The well known specialist in northern Salices Dr. Bjorn Floderus, 

 who has recently published an extensive study of the forms of Salix 

 in Greenland^, has been kind enough to examine the material brought 

 home by J. N. Nygaard. He names the forms present of follows: 



Most of the material and consequently the common form is the 

 supposed triple-hybrid : 



S. arctica Pall. x chloroclados Flod. x glauca L. It was found 

 in all the locahties visited on Inglelield Land (from Advance Bay to 

 the interior south of Rensselaer Bay) and was in flower from the 26' 

 June to over the middle of July. To this form also some twigs collected 

 in winter at Piteravik (Murchison Sound) are referred. 



1) Floderus, B.: Om Grønlands Salices. Medd. Grønl. LXIII, 1923. 



LXVIII; 2 



