36 Knud Jessen. 



Potentilla emarginata Pursh. 



Lit. Abromeit, 1899. Hartz, 1894, p. 32; 1895 a., p.288; 

 1895 b., p. 322. Ekstam, 1897. Simmons, 1906. Wolf, 1908. 



This plant is high northern and circumpolar. In Green- 

 land it lives on rocky and grassy flats; on Nova Zembla it 

 prefers dry slopes exposed to the sun (Ekstam). 1 



The alcohol material was collected in Greenland in dif- 

 ferent places. 



Pot. emarginata has a strong, multicipital primary root 

 which may attain a length of at least 25 cm. and a thickness 

 of 6 mm. During the first years the seedling is in the form 

 of a rosette without lateral shoots; the specimen figured has 

 just entered on its second- or perhaps its third summer 

 (Fig. 14, .4). Later on it branches freely and very compact 

 tufts rich in shoots, measuring as much as 20 cm. in diameter, 

 may be formed. Looser tufts are however often found; these 

 plants have probably lived in more favourable localities. 

 The shoots in such tufts are ascending or may at first have 

 a horizontal part several cm. in length. Often adventitious 

 roots, which may even be somewhat vigorous, arise from 

 older shoots, though this is hardly a normal occurrence, and 

 then vegetative propagation may take place or, rarely, even 

 a slight vegetative wandering may occur. The large brown 

 sheaths of the spirally arranged leaves persist for several 

 years, but the shoots may ultimately get rid of them. 



The floral shoots are lateral. They usually bear 1 — 2 

 leaves and are ascending or the lower portion is prostrate. 

 They are subtended by those leaves which in the autumn 

 occur uppermost in the rosette upon the monopodial main 



1 Ekstam (1. c.) records P. fragiformis Willd. from Nova Zembla, 

 but as this species, according to Wolf, does not occur on Nova 

 Zembla, he has probably had specimens of P. emarginata before him, 

 as these two species are commonly confused (cf. Wolf, p. 510). 



