[From the Bulletin of the Torrey Botanical Cub, 38; 79-89. igi 1 . | 



Notes on Rosaceae — V 

 POTENTILLA {Continued)* 



Per Axel Rydberg 



Frigidae 



In the North American Flora I recognized five species of this 

 group. No essential change was made from my treatment of the 

 group in my monograph, except that I united Potentilla nana 

 Willd. with P. emarginata Pursh. My conception of P. nana 

 had been that it was the same as P. fragiformis parviflora Traut., 

 i. e., a depauperate P. emarginata with blunter leaves, bractlets, 

 and sepals. Dr. Th. Wolf, who has seen the type of P. nana, 

 claims that it is a depauperate P. fragiformis instead. The main 

 distinction between P. emarginata and P. fragiformis, according 

 to Dr. Wolf, is that in the former the styles are scarcely longer 

 than the achenes, while in the latter they are fully twice as long. 

 In P. emarginata the styles are short, it is true, but as far as 

 P. fragifomis is concerned I have not been able to verify Dr. 

 Wolf's statement. In all the specimens at my disposal the 

 flowers are very young, and the achenes undeveloped, but the 

 styles do not seem very long. Dr. Wolf may be correct, however. 

 At all events P. nana should be reduced to a synonym. 



Dr. Wolf has also criticised my plate of P. fragiformis in my 

 monograph, and rightly so. In the specimen used for the illus- 

 tration of the plant, the petals had fallen, and I instructed the 

 artist to draw the flower from another specimen, which had better 

 flowers but was otherwise scrappy. Apparently he did not follow 

 my instruction, for the flower represents P. emarginata or P. nivea. 



Dr. Wolf divides the species of this group between his Ranun- 

 culoides and Aureae, referring P. flabelliformis and P. fragi- 

 formis to the former and the rest to the latter group. See my 

 remarks under the Aureae f group concerning this treatment. 

 P. Friesiana is regarded by Dr. Wolf as a ternate variety of the 

 quinate P. alpestris, i. e., P. macidata as understood in America. 



*See Bull. Torrey Club 37: 487-502. 28 O 1910. 

 fBull. Torrey Club 37: 495- 28 O 1910. 



79 



