182 ROSACEAE. 



Stem with spreading hairs ; leaflets cleft to near the mid-rib. 



12. P. brimnescens. 

 Leaves more or less tomentose beneath. 



Leaves sparingly tomentose and grayish beneath ; leaflets dissected about three- 

 fourths to the mid-rib. 13. P. Bakeri. 

 Leaves densely white-tomentose beneath ; leaflets merely crenate or toothed. 

 Lower stem-leaves 5-folioIate ; plant 3 dm. or more high. 



Hypanthium and calyx not tomentose, as well as the pedicels more or less 

 viscid ; pubescence of stem and petioles usually loose. 



14. P. Ulipes. 

 Hypanthium and calyx more or less tomentose, not viscid ; pubescence of 

 the stem and petioles usually appressed. 15. P. pulcherrima. 



Stem-leaves all ternate ; plant 1-2 (seldom 3) dm. high. 



8. P. quinquefolia. 



V. SUBJUGAE. 



One species. 16. P. subjuga. 



VI. NiVEAE. 



Stem 1-2 dm. high, more or less leafy, several-flowered. 17. P. nivea. 



Stem less than i dm. high, subscapose, usually 1-2 flowered. 18. P. uniHora. 



VIL MULTIFIDAE. 



Pubescence not silvery white. 

 Plant dark green ; branches of inflorescence rather long, erect. 



ig. P. atrovirens. 

 Plant usually yellowish green ; branches of inflorescence short and ascending. 



20. P. pennsylvanica. 

 Pubescence silvery white, at least beneath. 



Leaves white-silky on both sides ; lobes of the leaflets linear. 



21. P. bipinnatiUda, 

 Leaves greenish above ; lobes of the leaflets oblong or lanceolate. 



22. P. platyloba. 



VIII. RUBRICAULES. 



Sepals lanceolate to linear, acuminate. 



Leaves densely silky or tomentose on both sides. 23. P. HHcaulis. 



Leaves greenish above. 



Segments of the leaflets oblong to orbicular in outline. 



Stems decumbent or prostrate ; segments of the leaves oblong. 



24. P. rubripes. 

 Stems ascending ; segments of the leaves orbicular or nearly so. 



25. P. minutifolia. 

 Segments of the leaflets linear ; stems erect. 26. P. tenerrima. 



Sepals broadly ovate or ovate-triangular, obtusish or abruptly mucronate. 

 Plant densely cespitose ; leaves silky and finely tomentose beneath. 



27. P. saxi montana. 

 Plants with a few spreading branches ; leaves floccose beneath. 



6. P. concinna. 



IX. MULTIJUGAE. 



Leaflets dissected to near the mid-rib. 



Stem erect, with 1-3 small leaves. 28. P. pinnatisecta. 



Stem decumbent or ascending, leafy. 29. P. plattensis. 



Leaflets merely coarsely toothed ; stem erect. 30. R. rupincola. 



X. Leucophyllae. 



Leaves white-tomentose, floccose or silky, at least beneath. 



Bractlets nearly equalling the acute sepals ; leaves silky as well as tomentulose ; 

 hence shining. 



