ROSACEAE. 503 



Teeth of the leaflets acute; bractlets oblong. 



6. P. etnarginata. 

 Teeth of the leaflets obtuse; bractlets oval. 7. P. nana. 

 Flowers only 6 mm. broad. 8. P. Robbinsiana. 



Styles glandular-thickened below. 



Plants stout, erect, rough-pubescent. 



Stamens about 20. 9. P. Monspeliensis. 



Stamens 5-8; prairie species. 10. P. pentandra. 



Plant slender, often diffuse, villous or glabrate. 11. P. leucocarpa. 

 Leaves pinnately 3-11-foliolate. 



Leaves villous, or softly pubescent, rarely glabrate. 



All the leaves 7-1 i-foliolate; inflorescence cymose. 12. P. paradoxa. 

 Upper leaves 3-foliolate ; inflorescence falsely racemose. 



13. P. Nicollet it. 

 Leaves white-tomentose on both sides. 



Leaves mostly regularly pinnate ; pubescence silky and tomentose. 



14. P. Hippiana. 

 Leaves mostly interruptedly pinnate ; pubescence simply tomentose. 



15. P. effusa. 

 Leaves green above, white-tomentose beneath ; leaflets pinnatifid. 



Styles thickened at the base. 



Pubescence silvery-white. 16. P. bipinnatifida. 



Pubescence not silvery-white. 



Plants erect ; leaves 7-15-foliolate. 



Plant dark green; leaves scarcely paler beneath. 



17. P. atrovirens. 

 Plant not dark green ; leaves decidedly paler beneath. 



18. P. Pennsylvanica. 

 Plant ascending or decumbent; leaves 5-7-foliolate; leaflets ap- 

 proximate or almost digitate. 19. P. litoralis. 



Styles not thickened; plant low. spreading; leaves 5-9-foliolate. 



20. P. multifidn. 

 2. Flowers solitary, axillary; creeping or ascending plants. 

 Leaflets 5, rarely 3 ; petals and sepals 5. 



Stem long-assurgent ; first flower from the axil of the second stem-leaf or some 



subsequent leaf. 21. P. Canadensis. 



Plant low, less than 1 dm. high; first flower from the axil of the first stem-leaf. 



22. P. pumila. 

 Leaflets 3, rarely 5 ; petals and sepals 4, rarely 5. 23. P. procumbens. 



1. Potentilla argentea L. Silvery or Hoary Cinquefoil. (I. F. f. 

 1914.) Stems ascending, tufted, branched, slightly woody at the base. 1-5 dm. 

 long, white woolly-pubescent. Leaves all but the uppermost petioled, digitately 5- 

 foliolate: leaflets oblanceolate or obovate. green and glabrous above, white-pubescent 

 beneath, laciniate or incised and with revolute margins; flowers 4-8 mm. broad; 

 calyx-lobes ovate, acutish. a little shorter than the obovate refuse petals; stamens 

 about 20; style filiform. In dry soil. N. S. and Ont. to Dak., south to D. C. 

 and Kans. Also in Europe and Asia. May-Sept. 



Potentilla collina Wibel, of Europe, collected at Winona, Minn., and Cambridge, 

 Mass., differs in its more prostrate habit, broader, not revolute leaflets, and larger calyx. 



2. Potentilla maculata Pourr. Northern Cinquefoil. (I. F. f. 1915.) 

 Rootstock prostrate; stems ascending, simple, pubescent, 7-20 dm. high. Basal 

 leaves slcnder-petioled. digitately 5-foliolate (rarely 3-foliolate); leaflets obovate. gla- 

 brous above, pubescent along the margins and on the veins beneath, green both 

 sides, deeply toothed ; flowers few, terminal, loosely cymose; petals obovate, ob- 

 cordate. cuneate. orange-spotted at the base, longer than the ovate acutish calyx- 

 lobes; stamens about 20; style filiform. Lab. and Greenland to James Bay. Also 

 in Europe. Summer. [P. rubens Rydb.. not Vill.] 



3. Potentilla intermedia L. Downy Cinquefoil. (I. F. f. 1916.) Peren- 

 nial; stem 3-8 dm. hi^h. leafy, much branched, finely pubescent with long hairs. 

 Leaves green and finely hirsute on both sides, somewhat tomentose beneath, all but 

 the uppermost 5-foliolate; leaflets obovate or oblong, the teeth rather obtuse; flow- 

 ers numerous, cymose. leafy-bracted; petals obcordate, equalling the triangular- 

 ovate acute sepals and oblong bractlets; stamens about 20 ; style short. Mass., N. 



