566 



ROSACEAE 



Potentilla 



o ~w 

 Map 1151 



Potentilla arguta Pursh 



1. Potentilla fruticdsa L. (Dasiphora fruticosa (L.) Rydb.) Shrubby 

 Cinquefoil. Map 1150. This species prefers limy, springy places and 

 marshes and is more or less frequent in the lake area with a few outlying 

 posts south of it. 



Greenland and Lab. to Alaska, southw. to n. N. J., Pa., 111., Iowa, Ariz., 

 and Colo. ; also found in Eurasia. 



2. Potentilla arguta Pursh. (Drymocallis agrimonioides (Pursh) 

 Rydb.) Map 1151. This species is found in dry or moist sandy soil and 

 seems to prefer a prairie habitat. It is local to very local in the area shown 

 on the map and is most abundant in a remnant prairie in Lagrange County. 

 My specimens are all from roadsides and fallow fields. 



Eastern Que. and N. B. to Alaska, southw. to Va., Ill, Kans., and Colo. 



3. Potentilla Anserina L. (Argentina Anserina (L.) Rydb.) SiLVER- 

 WEED. Map 1152. Found only in beach pools along Lake Michigan. It was 

 formerly common just east of Michigan City but has become rare or ex- 

 tinct in most places. I have never found it in Porter County although 

 there is one report. The report from St. Joseph County should possibly 

 be referred to some other species. Grimes' specimen from Tipton County 

 was found in the railroad yards at Tipton. 



Arctic Amer., southw. to N. J., Ohio, Iowa, N. Mex., and Calif. 



4. Potentilla palustris (L.) Scop. (Comarum palustre L.) (Fernald & 

 Long. American variations of Potentilla palustris. Rhodora 16: 5-11. 

 1914.) Marsh Cinquefoil. Map 1153. This species prefers neutral or 

 slightly acid soils and is found mostly in marshes and swamps in the lake 

 area although it was found also in the Bacon Bog in Marion County. It is 

 variable in the pubescence of the leaflets. In the middle of September I 

 studied this species on the south shore of Long Lake in Porter County 

 where the shore is over a hundred feet wide. I was able to study the plants 

 from near the water line back to where it was too dry for the species to 



