154 ROSACE^E. (ROSE FAMILY.) 



compound leaves, and solitary or cymose flowers : their parts rarely in fours. 

 (Name a kind of diminutive from potens, powerful, alluding to the reputed medi- 

 cinal power, of which in fact these plants possess very little, being merely mild 

 astringents, like the rest of the tribe.) 



1 . Style terminal, or attached above the middle of the ovary : achenia glabrous. 



# Annuals or biennials : petals pale yellow, small, not exceeding the calyx : receptacle 



globular, ovoid, or even oblong in fruit. 



1. P. Norvegica, L. Hairy, erect, branched above; leaves palmately 3- 

 foliolale; leaflets obovate-oblong, cut-toothed. Fields: common, especially 

 northward. A homely weed. (Eu.) 



2. P. paradoxa, Nutt. Somewhat pubescent, spreading or decumbent, 

 branched; leaves pinnate; leaflets 5-9, obovate-oblong, cut-toothed; achenia 

 with a thick appendage at the base. Banks of the Ohio and Mississippi. 

 Shore of L. Ontario, J. A. Paine ; probably an immigrant from the West. 



# * Perennial herbs : petals yellow, commonly longer than the calyx. 

 i Low : leaves palmate, of 3 or 5 leaflets. 



3. P. frigida, Vffl. Dwarf (l'-3' high), tufted, vittous when young, 

 stems or scapes mostly 1 -flowered; leaflets 3, broadly wedge-obovate, deeply cut into 

 5-7 oblong approximate teeth. (P. Robbinsiana, OaTces.) Alpine summits 

 of the White Mountains of New Hampshire (Bobbins, Tuckennan, &c.). July. 



Less villous with age and smaller-flowered than P. frigida of the Alps, but 

 agreeing closer with it than with P. minima, which probably is only another 

 form of the same species. (Eu.) 



4. P. Canadensis, L. (COMMON CINQUE-FOIL or FIVE-FINGER.) Low 

 or dwarf, silky -hairy ; stems decumbent, prostrate, or at length creeping ; peduncles 

 axillary, 1 -flowered; leaflets 5, obovate-wedge-form, cut-toothed towards the apex. 



Dry soil. April -July: producing summer runners (P. sarmentosa, Muhl.). 

 Var. simplex, Torr. & Gr. Less hairy and greener, larger, the ascending 



stems (l-2 long, seldom if ever creeping) from a thicker and harder caudex: 

 leaflets obovate-oblong, sometimes almost glabrous. (P. simplex, Michx.) 

 Meadows or moister soil. May- Sept. Usually appearing distinct. 



5. P. argentea, L. (SILVERY CINQUE-FOIL.) Stems ascending, panicu- 

 lately branched at the summit, many-flowered, white-woolly ; leaflets 5, wedge-oblong, 

 almost pinnatifid, entire towards the base, with revolute margins, green above, 

 white with silvery wool beneath. Dry barren fields, &c. June- Sept. (Eu.) 



- H- Leaves pinnate, of 3 - 9 leaflets. 



6. P. Pennsylvania, L. Stems erect (5'- 1 8' high), hairy or woolly ; 

 cymose at the summit, many-flowered ; leaflets 5-9, oblong, obtuse, pinnatifid, 

 silky or downy with white hairs, especially beneath, the upper ones larger and 

 crowded; petals scarcely longer than the calyx. Pennsylvania'? New Hamp- 

 shire (Isle of Shoals, Robbins), Maine (Cape Elizabeth, C. J. Sprague), N. Wis- 

 consin, and northwestward. July -Aug. 



2. Style deeply lateral : petals yellow or white, deciduous. 

 * Achenia glabrous: style thickened upwards: receptacle conical, in fruit. 



7. P. arguta, Pursh. S tern erect and stout (1- 4 high,) brownish-hairy, 

 clammy above ; leaves pinnate, of 3 - 9 oval or ovate cut-serrate leaflets, downy 



