ti 



Knud Jessen. 



Potentilla palustris (L.) Scop. 



Lit. Irmisch, 1861. Lindman, 1884. Warming, 1884. Knuth, 

 1894. Kölpin Kavn, 1894. Norman, 1895. Astrid Cleve, 1901. 

 Freidenfelt, 1904. Sylvén, 1906. Wolf, 1908. 



Potentilla palustris is widely distributed over a great 

 part of the northern hemisphere. It lives in Arctic and Sub- 

 arctic regions and extends southwards as far as 40° N. lat. ; 

 and the monographer of the Potentillas, Th. Wolf (1. c), 



Fig. 1. Potentilla palustris. 



(Denmark, Oct. 20, 1912 ; about Va). The leaves are dead, n, n, Scale-leaves of the winter 

 bud, 1911 — 1912 ; its internodes are slightly elongated ; a, b, c, d, foliage-leaves on axis I 

 unfolded during early summer; i, floral axis; c subtends the principal shoot II with 

 the leaves 1 — 5 which have unfolded during summer; b subtends a "supplemental shoot 

 ("Bereicherungsschuss"). 



states that it is highly probable that the species is a remnant 

 of the Arctic tertiary flora and that it has doubtless only 

 recently — perhaps during the Glacial period — advanced south- 

 wards. It is everywhere confined to boggy and peaty soil 

 and thrives best at the edge of swamps and high-moors among 

 the peat-forming mosses. Norman (1. c.) writes that in Arctic 

 Norway it frequently occurs on the strand and he believes 

 that it is in part distributed by ocean-currents. 



The alcohol material on which the following description 

 is based was collected in Greenland and in Denmark. 



