154 ROSACEA. (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, heing 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 



globidar, ovoid, or even oblong in fruit. 



1. P. Norvegica, L. Hairy, erect, branched above; leaves palmate/y 3- 

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

 northward. A homely weed. (Eu.) * 



2. P. parad6xa, 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: 

 ■*- Low: leaves palmate, of 3 or 5 leaflets. 



3. P. frigida, Vill. Dwarf (l'-3' high), tufted, villous when young, 

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

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

 of the White Mountains of New Hampshire (Robbins, Tuckerman, &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, Miclix.) — 

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



5. P. argentea, L. (Silvery Cinque-foil.) Steins 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.) 



-i- «- Leaves pinnate, of 3-9 leaflets. 



6. P. Pennsylvaniea, L. Stems erect (5'- 18' 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 1 ? 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 f nut. 



7. P. argilta, Pursh. Stem erect and stout (1°- 4° high,) brownish-hairy, 

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



