ROSE FAMILY 159 



b. Achenes without a swelling 



(1) Flowers mostly 8-12 mm. wide; stamens 



15-20 P. monspeliensis 



(2) Flowers mostly 4-6 mm. wide; stamens 



5-10 P. rivdlis 



2. Flowers fewer and cymes less leafy ; leaves most- 

 ly of 5-many leaflets; style not swollen at the 

 base, except in perennials with well-developed 

 rootstock 



a. Leaflets digitate 



(1) Leaflets 3, white-woolly beneath; style 



swollen toward the base P. nivea 



(2) Leaflets 5-many 



(a) Stems tufted, spreading, 1-4 in. high; 



leaflets 5, white-woolly beneath P. concinna 



(b) Stems mostly erect, .5-3 ft. high; leaflets 



5-9 

 x. Leaflets toothed or cleft to the base or 



nearly, smooth to white-woolly P. grdcilis 



y. Leaflets toothed or cleft little below the 



middle P. dissecta 



b. Leaves pinnate, of 5-many leaflets 



(1) Leaflets 5-7, small, usually less than .5 in. P.rubricdulis 



long 



(2) Leaflets mostly 7-many, .5-3 in. long 



(a) Style not longer than the mature achene, 



swollen below ; leaflets mostly cleft or 



divided, green to white-woolly P. pennsilvdnica 



(b) Style usually longer than the mature 



achene, hardly or not at all swollen 

 below ; leaves silky-white to felted or 

 nearly green; leaflets toothed to di- 

 vided 



x. Leaves mostly gray-woolly on one or 

 both sides, more rarely green and 

 smoothish ; leaflets mostly 1-3 in. long P. hippidna 

 y. Leaves mostly green and smooth, more 

 rarely white-hairy; leaflets mostly .5- 

 1 in. long 



(x) Leaflets toothed P.crinita 



(y) Leaflets cleft or divided P.plattensis 



