80 Rydberg: Notes on Rosaceae 



BlFLORAE 



This group consists of but one species. Dr. Wolf places the 

 group in his section Potentillae trichocarpae subsection 

 Nematostylae, i. e., in a section with hairy ovaries and the fili- 

 form style attached at or below the middle of the ovary. The 

 only American species that should be counted to this section is P. 

 tridentata or my genus Sibbaldiopsis. In his characterization of 

 the group, Dr. Wolf states that the achenes of P. biflora only have 

 a bunch of hairs at the scar of insertion. So far as I know they 

 are not hairy at all and the bunch of hairs referred to are the hairs 

 of the receptacle found in all the Potentillae. These are unusually 

 long in P. biflora. The style in this species is also almost terminal, 

 just as in many typical species of the genus. It is evident that 

 Dr. Wolf has placed this as well as P. palustris in a wrong division 

 of the genus. 



Saxosae 



This group consists of three species from Southern California 

 and Lower California . They have much the habit of certain species 

 of Ivesia, and for some time I regarded the first known species 

 of the group, Potentilla saxosa, as a member of Ivesia. Dr. Wolf 

 places P. saxosa and P. rosulata in the Multijugae group, but 

 I think that they differ enough from that group to constitute a 

 group by themselves. P. acuminata Hall is so closely related to 

 these that I was strongly inclined to reduce it to a synonym of 

 P. rosulata. The only essential differences are the thinner leaves 

 and narrower bractlets. Dr. Wolf places it in the Ranuncu- 

 loides group (a group with digitate leaves), perhaps because the 

 plant is glandular, as is P. brevifolia, another pinnate-leaved 

 species referred to the same group by him. On account of the 

 glandular pubescence, Hall thought at first the plant related to 

 the Glandulosa group, i. e., the genus Drymocallis, and also com- 

 pares it with P. brevifolia. The latter could easily be taken for a 

 species of Drymocallis, if the style is disregarded; but P. acuminata 

 does not resemble a species of that genus so much. Dr. Wolf 

 remarks: "What separates P. acuminata not only from all other 

 species of this group [Ranunculoides of Wolf] but also from all 

 other known Potentillas of the Earth — with the exception of 



