550 



PROCEEDINGS OP THE AMERICAN ACADEMY 



Leaflets 5 - 9 ; cyme fastigiate ; stamens 25, some- 

 times 20 6 



Leaflets 3 ; cyme close ; stamens 20 ; low 

 Leaflets 3 - 5 ; flowers 1-3, on slender pedicels ; 



stamens 20 ; low, arctic 



II. Styles filiform ; inflorescence terminal. 

 * Style terminal (nearly so in P. brevifolia) ; carpels gla- 

 brous ; disk not thickened ; stamens 20 ; herbaceous 

 perennials, with rather large yellow flowers, 

 t Leaves pinnate (sometimes digitate in Nos. 9 and 14) ; 

 carpels 10 - 40 ; bractlets shorter than the sepals. 

 Leaflets 5-11, white-tomentose, at least beneath, 

 diminishing uniformly down the petiole ; carpels 



10-30 



Leaflets 5-11, white-tomentose, the alternate ones 



smaller; carpels 10 



Appressed silky-villous ; stems decumbent ; leaflets 



9-15, folded, falcate; carpels 25 -30 

 Low, alpine or subalpine ; flowers few. 



"White-tomentose; leaflets 7-13, broadly cuneate ; 



flowers rather large in a close cyme 

 Silky-villous or subglabrous ; leaflets 7-13, small, 

 broadly cuneate ; flowers small, in an open cyme . 

 Subglabrous or silky-villous; leaflets 5 - 7, rarely 3, 



often digitate 



1 1 Leaves digitately 5 - 7-foliolate (rarely pinnate in P. 

 gracilis) ; tomentose or villous. 

 Leaflets 5-7, rarely 3 ; bractlets shorter than the 



sepals ; carpels more than 40 ; Western 

 Leaflets 5, white-tomentose beneath, smooth above ; 

 bractlets and sepals equal ; carpels more than 40 ; 



Eastern 



Leaflets 5, toothed only at the apex, tomentose and 

 villous; stems decumbent ; carpels 15-20 

 A 1 1 Leaves ternate (quinate in P. maculata) ; low, arctic 

 or alpine, few-flowered ; carpels 15-40. 

 Tomentose and villous ; bractlets acute 

 Villous or densely tomentose ; bractlets obtuse ; 



Alaska 



Sparingly villous or subglabrous. 

 Leaflets 5, rarely 3 ; bractlets shorter than the 



sepals ; Labrador and Greenland . 

 Flowers mostly solitary ; bractlets and sepals 

 equal, obtuse ....... 



Nearly glabrous ; flowers 1 - 3 ; bractlets and 

 sepals nearly equal ; Oregon .... 



P. Pennsylvanica. 

 7. P. Hoolceriana. 



8. P. pulchella. 



9. P. Eippiana. 



10. P. effusa. 



11. P. crinita. 



12. P. Breweri. 

 13. P. Plattensis. 



14. P. dissecta. 



15. P. gracilis. 



16. P. argentea. 

 17. P. humifusa. 



18. P. nivea. 

 19. P.fragiformis. 



20. P. maculata. 



21. P. emarginata. 



22. P. gelida. 



