14 Knud Jessen. 



Th. Wolf, on the other hand, states that they fall off after 

 flowering. The flower-biology has been exhaustively des- 

 cribed by Heinsius^ and Knuth (1. c.) from Hofland and from 

 the North Frisian Islands respectively; unfortunately my 

 Greenland material contained only a very few flowers, but 

 they corresponded with the descriptions of the above authors 

 in being decidedly proterandrous. According to Knuth Po- 

 tentilla palustris behaves as follows: Shortly after the young 

 flower has expanded, the extrose anthers on the numerous 

 erect stamens open; when the anthers have fallen off the 

 filaments bend outward toward the calyx and the corolla so 

 that room is made for the stigmas which are now furnished 

 with small, yellow stigmatic papillæ. The flowers are eagerly 

 visited by bees. Honey is secreted by a green disk between 

 the carpels and the stamens; this had already been observed 

 by Konrad Sprengel. Norman writes that the great amount 

 of honey contained in the flowers attracts numerous insects, 

 flies, butterflies and bees, which continue to visit the flower 

 a long time after fertilization has taken place. 



The time of flowering is in Central Europe in June and 

 July; in Arctic Norway it begins about July 20; in the moun- 

 tains of northern Sweden it is recorded to be in August, in 

 Greenland in July and August. In specimens from Denmark 

 I found young flower-buds in the beginning of May, while 

 such were not found in the middle of March. So the flower- 

 development probably begins at the same time as the closely 

 folded winter-bud begins to open. In some of the northern- 

 most localities of Arctic Norway it may happen that flowers 

 are not developed. Miss Cleve found no fruit in the mountains 

 of northern Sweden. 



The theory advanced by Norman that in the coastal 

 districts of Norway Potentilla palustris is dispersed by 

 marine currents is borne out by the fact that the fruit is 

 > Bot. Jaarboek, 1892, Tab. II, figs. 7—9. 



