ROSACEAE. 181 



Leaves mainly digitate, rarely pinnate with approximate leaflets or with a pair 

 of small leaflets on the petioles. 

 Leaves or at least the basal ones 5-9-foliolate. 



Additional smaller leaflets on the petioles not present. 

 Plants less than 2 dm. high. 

 Leaves tomentose at least beneath. 

 Leaves not tomentose. 

 Plants more than 2 dm. high. 

 Additional smaller leaflets on the petioles present. 

 Leaves 3-foliolate, tomentose beneath. 

 Leaves manifestly pinnate. 



Style not longer than the mature achenes, thickened or glandular below ; leaves 

 more or less tomentose, but not necessarily white beneath. 



Style much longer than the mature achenes. filiform. 

 Leaflets approximate, 3-7. 



Leaves tomentose beneath. 



Leaves not at all tomentose. 

 Leaflets rather distant 7-21. 



Leaves green on both sides and only slightly hairy. 



IX. MULTIJUGAE. 



Leaves grayish or whitish, silky or tomentose. X. Leucophyllae. 



I. SUPIXAE. 



Achenes with a corky gibbosity on the upper suture ; leaves pinnate with 3-5 

 pairs of leaflets. i. P. paradoxa. 



Achenes not gibbous. 



Leaves pinnate, with 2 approximate pairs of leaflets ; the upper ternate. 



2. P, rivalis. 

 Leaves all ternate (or the lower rarely digitately 5-foliate). 



Petals shorter than the sepals ; achenes whitish. 



Stem difi^usely branched, spreading ; leaflets cuneate ; inflorescence cymose. 



3. P. leucocarpa. 

 Stem erect, strict ; leaflets broadly obovate ; inflorescence falsely racemose. 



4. P. lateriflora. 

 Petals about equalling the sepals ; stem stout, strict ; achenes brownish. 



5. P. monspeliensis. 



II. CONCINNAE. 



Middle leaflet sessile. 



Leaflets obovate or cuneate, deeply toothed or incised. 6. P. concinna. 



Leaflets oblong, with entire margins, only 3-toothed (rarely s-toothed) at the 

 very apex. 7. p. hicrenata. 



Middle leaflet petioled. 8. P. quinquefolia. 



III. Aureae. 

 Only one species. 9. p, dissecta. 



IV. Graciles. 



Leaves green on both sides, not at all tomentose beneath. 



Leaflets cuneate at the base, usually toothed only above the middle ; plants low, 



usually less than 3 dm. high. 9. P. dissecta. 



Leaflets oblanceolate, toothed to near the base ; plants 3-6 dm. high. 



Stem glabrous or appressed-pubescent ; leaflets coarsely toothed or cleft half- 

 way to the mid-rib or less. 

 Slender ; leaves thin, not strongly ribbed ; inflorescence open ; bracts small. 



10. P. jucunda. 

 Stout ; leaves thick and strongly ribbed ; inflorescence dense ; bracts con- 

 spicuous. II. p. Nuttallii. 



