Rydijekg : Notes on Rosaceae 381 



page 25), after Clute had reported P. canadensis and P. pumila as 

 growing together on the sand barrens of Long Island and were 

 "connected through intermediate forms." The page referred to 

 contains the proceedings of the Club. I had nothing to do with 

 it and my name was not even mentioned. Clute's report on the 

 sand barren flora contains a statement very opposite to what 

 Dr. Wolf gives, viz. : "Potentilla pumila and P. canadensis growing 

 together without intermediate forms." Robinson and Fernald, 

 who give Potentilla a very conservative treatment in Gray's 

 New Manual, keep them distinct, although they regard P. simplex 

 a variety of P. canadensis. I for some time thought that an 

 additional species could be distinguished from P. canadensis, viz., 

 the plant common in the lower Mississippi Valley. This has 

 much thicker and more shining leaves and usually longer bractlets 

 than the common P. canadensis of the North Atlantic States, but 

 these characters were found to be too unstable and the plant 

 grades so into the typical form that the idea was given up. 



Heterosepalae 

 This group contains only one species from Mexico and Central 

 America. Dr. Wolf refers it to the Supinae group, perhaps rightly 



so. 



Supinae 



In the North American Flora 12 species are admitted. Of 

 these, Potentilla rivalis, P. millegrana, P. biennis. P. michoacana 

 and P. pentandra are regarded by Dr. Wolf as distinct species ; and 

 P. paradoxa and P. monspeliensis are regarded as varieties of the 

 European P. supina and P. norvegica respectively. P. Nicolletii 

 is made a mere form (f. decumbens) of P. supina paradoxa. A 

 comparison between this treatment and the one in Gray's New 

 Manual is rather interesting. In that publication P. Nicolletii 

 is regarded as a good species, while P. millegrana and P. pen- 

 tandra are made varieties of P. rivalis. Whatever may be said, 

 Potentilla Nicolletii is a rather weak species, while P. pentandra 

 is one of the most distinct in the group. Opiz even based a new- 

 genus on the same. It is also interesting to know that the speci- 

 men which Sheldon had most in mind when he raised P. Nicol- 

 letii to specific rank and which he distributed under that name, 



