l04: KOSACK^. (kOSK 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, beinjj; merely mild 

 astringents, like the rest of the tribe.) 



§ 1. Sti/le terminal, or atiachid altove the jniddle of the ovary: achenia glabrous. 



* Annuals or bieinikils: petals pale j/ellow, sniall, not exceeding the calyx: receptacle 



glolndar, ocoid, or even oblong in J"/ nil. 



1 . P. Noi'Vfegica, L. Hairy, erect, branched ai)ove ; leaves palmatelg 3- 

 foliolali'.; leaflets ol)ovatc-oblong, cut-tootlicd. — Fields: connnon, especially 

 northward. A homely weed. (Eu.) 



2. P. parad6xa, Nutt. Somewhat pubescent, spreading or decumbent, 

 branched; leurcs /linnute; leaflets 5-9, obovate-oblong, cut-toothed; achenia 

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

 Shore of L. Ontario, ./. A. P«/ne ; .probably an immigrant from the West. 



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

 -.- Low: hares piihwite, of 3 or 5 leaflets. 



3. P, frigida, Vill. Da-aif {V -^' high), tufted, villous when young, 

 stems or scapes mostly 1 -flowered ; Uaflels 3, bro.idly iv-dge-oborate, deeply cut into 

 5-7 oblong approximate teeth. (P. Kobbinsilina, Oalts.) — Alpine summits 

 of the White Mountains of New Hampshire (/^'oWwi/s, Tuckrrnian, &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, ^1. (Commox Cixque-foil or Five-Finger.) Low- 

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

 axillarv, 1-flowercd ; leaflf-ts 5, obovate-wedge-forin, citt-toothfd towards the apex. 



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

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



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

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

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



5. P. argentea, L. (Silvery Cixque-foil.) Stems ascending, pr/n/ni- 

 lately branched (it the summit, many-floicrred, white-woolly ; leaflets 5, wedge-oblong, 

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

 white with silvery tcool l>eneath. —Dry barren fields, &c. June- Sept. (Eu.) 



-;- -t- hnrrs pinnate, of 3-d leaflets. 

 G. P. Pennsylv^nica, 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; pet<'\ls scarcx^ly longer than the calyx. — Pennsylvania^ New Hamp- 

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

 consin, and northwestward. July -Aug. 



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



* Achenia ghihrous : style thich-ened upiciirds : receptacle conical in fruit. 



7. P. argilta, Pursh. Stem ereetand stout (l°-4° high,) brownish-hairy, 



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



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