ROSACEAE (ROSE FAMILY) 481 



15. POTENTILLA L. CINQTJEFOIL. FIVE-FINGER 



Calyx flat, deeply 5-cleft, with as many bractlets at the sinuses, thus appear- 

 ing 10-cleft. Petals 5, usually roundish. Stamens many. Achenes many, col- 

 lected in a head on the dry mostly pubescent or hairy receptacle ; styles lateral 

 or terminal, deciduQus. : Radicle superior. Herbs, or rarely shrubs, with com- 

 pound leaves, and solitary or cymose flowers ; their parts rarely in fours. (Name 

 a diminutive from potens, powerful, originally applied to P. Anserina, from its 

 once reputed medicinal powers.) 



a. Petals reddish-purple 14. P. palustris. 



a. Petals yellow or white b. 



b. Stems shrubby 15. P.fruticosa. 



b. Stems herbaceous c. ; 



c. Flowers solitary, on naked peduncles from the axils of the foliage- 

 leaves or on the stolons. 



Leaves pinnate, of numerous leaflets 17. P. Anserina. 



Leaves palmate, of 3-5 leaflets. 



Tufted alpine plant 11. P. Robbinsiana. 



Plants with elongate slender stems. 

 Earliest flower from the node above the first well-developed 



internode 18. P. pumila. 



Earliest flower from the node above the second or third well- 

 developed internode. 



Stems ascending or procumbent, not repent . . . 19. P. canadensis. 

 Stems repent. 

 Leaflets mostly 5, spatulate-oblong, finely crenate-den- 



tate nearly to the base 20. P. reptans. 



Leaflets mostly 3, cuneate-obovate, coarsely incised 



chiefly above the middle 21. P. procumbens. 



c. Flowers cymose, or if solitary in the axils of reduced upper 



leaves d. 

 d. Leaves pinnate. 



Inflorescence glandular-viscid 1. P. aryuta. 



Inflorescence not glandular. 

 Leaves white-pubescent above. 

 Pubescence of the leaves lustrous and silky . . .12. P. Hippiana. 



. Pubescence a dull tomentum 18. P. effusa. 



Leaves green or greenish above. 

 Leaves definitely pinnate, the leaflets essentially uniform ; 



cyme very leafy 4. P. paradoxa. 



Leaves seemingly palmate, the leaflets crowded and the 

 lower ones much smaller than the others. 



Cyme very leafy ; petals minute 8. P. rivalis. 



Cyme scarcely leafy ; petals showy . . . 6. P. pennsylvanica. 



d. Leaves palmate e. 



e. Petals 'white ; leaflets toothed only at tip 16. P. tridentata. 



e. Petals yellow ; leaflets toothed along the sides /. 



/. Tufted alpine plant with 1-2-flowered short branches . . 11. P. Robbinsiana. 

 f. Leafy-stemmed plants with cymose flowers g. 

 g. Petioles and lower part of stem hirsute. 



Leaflets 3 ; petals about as long as the calyx-lobes . 2. P. monspeliensis. 

 Leaflets 5-7 ; petals much exceeding the calyx-lobes ' . 10. P. recta, 

 g. Petioles and stems woolly or tomentulose h. 



h. Leaves silvery-white beneath 7. P. argentea. 



h. Leaves green or at most slightly grayish beneath ?'. 

 i. Plants loosely branched, with very leafy diffuse cymes. 



Perennial ; petals obcordate 8. P. intermedia. 



Annual or biennial ; petals narrowly cuneate. 



Achenes strongly gibbous on the ventral side . 5. P. Nicolletii. 

 Achenes not gibbous on the ventral side . 8. P. rivalis. 



i. Plants with simple stems and scarcely leafy corymbi- 



form cymes 9. P. Nuttallii. 



1. Styles thickened and glandular toward the base ; achenes glabrous, numer- 

 ous ; inflorescence cymose. 



* Style nearly basal ; stamens 25-30 ; perennial glandular-villous herbs, with 

 pinnate leaves, and rather large white or yellow petals. 



1. P. arguta Pursh. Stems erect, usually stout, 3-10 dm. high, brownish- 

 hairy, clammy above ; leaflets 7-11, oval or ovate, cut-serrate, downy beneath ; 

 cyme strict and rather close ; stamens mostly 30, on a thick glandular disk. 

 (Drymocallis Rydb.) Rocky, gravelly, or alluvial soils, e. Que. to D. C., and 

 westw. June, July. 



GRAY'S MANUAL 31 



