GENUS 7. 



ROSE FAMILY. 



2 55 



14. Potentilla nivea L. Snowy Cinquefoil. Fig. 2240. 



Potentilla nivca L. Sp. PI. 499. 1753. 



Stems 2'-6" high, woody at the base, ascending or 

 erect, silky-villous, the flowering ones mostly simple. 

 Stipules membranous, silky; leaves 3-foliolate (very 

 rarely 5-foliolate), the lower petioled; leaflets obo- 

 vate, oblong or oval, obtuse, incised-dentate or cre- 

 nate, densely white-pubescent beneath, green and 

 loosely villous above, 4" -8" long, the terminal one 

 generally cuneate, the others narrowed or rounded 

 at the base ; flowers 1-5, terminal, pedicelled, yellow, 

 S"-g" broad ; bractlets lanceolate to linear ; sepals 

 silky, lanceolate, acute, shorter than the broadly 

 obovate emarginate petals, longer than the bractlets ; 

 stamens about 20 ; style filiform, terminal ; achenes 

 glabrous. 



Quebec, Labrador, Greenland and throughout arctic 

 America to Alaska and British Columbia, south in the 

 Rocky Mountains to Utah and Colorado. Also in arctic 

 and alpine Europe and Asia. Summer. 



Potentilla Vahliana Lehm., another high boreal spe- 

 cies, differs in having oval or ovate bractlets and leaflets 

 yellowish-villous beneath. 



15. Potentilla emarginata Pursh. Arctic 

 Cinquefoil. Fig. 2241. 



Potentilla emarginata Pursh, Fl. Am. Sept. 353. 

 1814. 



Potentilla nana Willd. ; Schlecht. Berl. Mag. 7 : 

 296. 1815. 



Stems villous-pubescent, tufted, ascending 

 or erect, i'-4' high. Stipules ovate or oblong, 

 membranous, mostly obtuse, entire; leaves 

 3-foliolate, the basal slender-petioled ; leaflets 

 obovate, 2"-6" long, incised-dentate with acute 

 teeth, of which the terminal one is generally 

 the largest, generally villous on both sides, 

 the terminal one narrowed or cuneate, the 

 others sometimes broad at the base ; flower 

 solitary, rarely 2, yellow, 5 "-7" broad; calyx- 

 lobes ovate, obtuse, pilose, equalling the ob- 

 long bractlets, shorter than the obovate ob- 

 cordate petals ; stamens about 20; style filiform; 

 achenes glabrous. 



Labrador, Greenland and arctic America to 

 Alaska. Also in eastern Siberia and Spitzbergen. 

 Summer. 



Robbins' 



1 6. Potentilla Robbinsiana Oakes. 

 Cinquefoil. Fig. 2242. 



Potentilla Robbinsiana Oakes ; T. & G. Fl. N. A. i : 441. 1840. 



Potentilla minima A. Gray. Man. 122. 1848. 



P. frigida A. Gray, Man. Ed. 5, 154. 1867. Not Vill. 1789. 



> Depressed, -2' high, tufted from a thick woody base, 

 villous-pubescent. Stipules ovate, obtusish, loosely villous ; 

 basal leaves petioled, 3-foliolate, those of the flowering 

 stem sessile, small and 3-lobed; leaflets obovate, villous on 

 both sides, and especially so beneath, 2"-4" long, deeply 

 3~7-dentate above, cuneate or narrowed at the base, obtuse 

 at the apex ; flowers solitary, terminal, slender-petioled, yel- 

 low, about 3" broad ; sepals and bractlets nearly equal, 

 obtuse, slightly shorter than the obcordate petals ; stamens 

 about 20; style filiform; achenes glabrous. 



White Mountains of New Hampshire. Summer. 



