412 ROSACEAE 



Stem and mature leaves more or less hairy; leaflets obovate, at least the upper 



pinnatisect. 

 Divisions of the leaflets long, narrowly linear; stem 2-3 dm. high; leaflets 



many. 66 - p - wyomingensis. 



Division's of the leaflets oblong or oblanceolate; stem less than 2 dm. high; 



leaflets few. 67. P. ovina. 



Leaflets not dissected to near the midrib. 

 Leaves not densely grayish-strigose. 



Sepals ovate or lance-ovate; bractlets lanceolate or oblong. 



Stem about 1 dm. high; leaflets 1 cm. long or less, toothed only at the apex. 



65. P. decurrens. 



Stem 2-4 dm. high; leaflets more than 2 cm. long. 68. P. Drummondii. 

 Sepals linear -lanceolate, acuminate; bractlets linear-subulate. 



54. P. rupincola. 

 Leaves densely grayish-strigose or silky. 



Stem 1^: dm. high, ascending or decumbent; leaflets cuneate or linear-oblong, 



conduplicate, toothed at the apex only. 69. P. crinita. 



Stem stout, 6-7 dm. high; leaflets obovate-oblong, coarsely serrate. 



62. P. ambigens. 



XV. MULTIFIDAE. 



Pubescence of the under side of the leaves silvery-white. 



Petioles and lower part of the stem silky villous with spreading hairs. 



70. P. paucijuga. 

 Petioles and stem tomentulose and silky strigose. 



Segments of the leaflets linear or linear-oblong; branches of the inflorescence 



usually short and ascending. 

 Leaflets usually white on both sides; petals and sepals 4-6 mm. long. 



.Stem decumbent or ascending, 0.5-1 dm. high; leaflets 2 or 3 rather approx- 

 imate pairs. 71. P. pseudpsericea. 

 Stem erect, 3-5 dm. high; leaflets 3-7 usually rather remote pairs. 



72. P. bipinnatifida. 

 Leaflets green above; petals and sepals about 3 mm. long. 



73. P. virgulata. 

 Segments of the leaflets lanceolate or oblong, usually green above; branches of 



the inflorescence long and erect. 74. P. platyloba. 



Pubescence of the under side of the leaves grayish. 

 Petioles and stem appressed-pubescent. 



Segments of the leaflets narrowly linear; petals and sepals about 3 mm. long. 



73. P. virgulata. 

 Segments of the leaflets ovate, lanceolate, or oblong; petals and sepals 4-6 mm. 



long. 

 Leaves glandular-pruinose above and sometimes with scattered long hairs. 



75. P. glabrella. 

 Leaves short-strigose above. 



Margins of the leaf-segments not revolute. 76. P. pennsylvanica. 



Margins of the leaf-segments revolute. 77. P. arachnoidea. 



Petioles and stem with spreading hairs. 



Flowers distinctly pedicelled; upper leaflets of the basal leaves with 9-13 segments; 



pubescence of the stem and petioles long. 



Plant dark green; leaves scarcely paler beneath. 78. P. atrovirens. 



Plant not dark green; leaves decidedly paler beneath. 79. P. strigosa. 

 Flowers usually subsessile, densely conglomerate; upper leaflets of the basal leaves 

 with 15-21 segments; pubescence of the stem short and dense. 



80. P. lasiodonta. 



1. P. paradoxa Nutt. Stem spreading or ascending, seldom erect, about 

 2-5 dm. high, leafy; leaves in age nearly glabrous, light green in color; leaflets 

 obovate-cuneate, deeply crenate or cleft, 1-2 cm. long; flowers about 7 mm. in 

 diameter; bractlets and sepals oblong-ovate, acute or mucronate, about equal in 

 length; petals yellow, obovate-cuneate, truncate or slightly emarginate; stamens 

 15-20. Low ground : N.Y.Ont.N.M. Utah Wash.; Mex., e Asia. Plain 

 Submont. Je-Au. 



2. P. rivalis Nutt. Stem erect and simple, finely villous-hirsute, leafy; 

 leaflets 2-5 cm. long, obovate, with coarse ovate teeth; flowers less than 5 mm. 

 in diameter; bractlets oblong, obtuse or acute, rather shorter than the ovate 

 acute sepals; petals cuneate, much shorter than the sepals; stamens about 10. 

 River valleys: B.C. Sask. Mex. Plain Submont. Je-Au. 



3. P. millegrana Engelm. Stem slender, 4-8 dm. high, divaricate, softly 

 pubescent, sometimes nearly glabrous; leaves ternate, finely pubescent; leaflets 

 oblong-cuneate, deeply serrate, 1-6 cm. long, the middle one often petiolulate; 

 flowers 3-4 mm. in diameter; bractlets and sepals oblong-ovate, acute, of about 

 the same length; petals oblong-cuneate, about half as long as the sepals, light- 

 yellow; stamens generally 10; achenes smooth, light-colored, small. P. leuco- 



