80 RYDBERG: NOTES ON ROSACEAE 
BIFLORAE 
This group consists of but one species. Dr. Wolf places the 
group in his section POTENTILLAE TRICHOCARPAE subsection 
NEMATOSTYLAE, i. e., ina 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 toa 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 
ie» Peers 
