ROSACES. (ROSE FAMILY.) 83 



Var. Illinoensis, Gray. A coarser or larger plant, perhaps a distinct 

 species : the flowers more inclined to be polygamo-dicecious : the villous hairs of the 

 scape and pedicels widely spreading. The common form in the mountains 

 and extending eastward to the Atlantic States. 



Yar. glauca, Watson. Differs from the type in the perfectly smooth and 

 glaucous surface of the leaf, Bot. King's Exp. 85. In the Wahsatch and 

 Uinta Mountains. 



2. P. veSCelj !/ Akenes superficial on the glabrous conical or hemispherical 

 fruiting receptacle (not sunk in pits) : calyx remaining spreading or reflexed : 

 hairs on the scape mostly widely spreading, on the pedicels appressed : leaflets thin, 

 even the upper surface strongly marked by the veins. Throughout the 

 United States and Arctic America. 



16. POTENT ILL A, L. FIVE-FINGER. 



Petals 5, obcordate or broadly obovate. Styles lateral or nearly terminal, 

 short, deciduous. Akenes small, turgid, crustaceous. Herbaceous or rarely 

 woody : flowers cymose, or axillary and solitary. Watson, Proc. Am. Acad. 

 viii. 549. 



* Styles thickened and glandular toward the base : carpels glabrous, sessile : in- 

 florescence cymose. 



<- Style attached below the middle of the ovary : disk thickened : stamens 25 to 

 30 : perennial herbs with glandular -villous pubescence and pinnate leaves. 



1. P. arguta, Pursh. Stem erect and stout, 1 to 4 feet high, simple 

 below : radical leaves 7 to 1 1 foliolate ; leaflets rounded, ovate, or subrhom- 

 boidal, incised or doubly serrate : cyme strict and rather close; calyx densely 

 pubescent : stamens mostly 30. New Mexico and northward to N. Idaho, thence 

 eastward to the New England States and Canada. 



2. P. glandulosa, Lindl. Resembling the last, but usually more slender 

 and branched, 1 to 2 feet high, and for the most part less pubescent : leaflets 

 more frequently 5 to 9: cyme panided, with elongated branches and more slender 

 pedicels : calyx much less tomentose : stamens usually 25. P. fissa, Nutt. In 

 the mountains, from New Mexico and Colorado northward, and thence west- 

 ward to California and Washington Territory. 



H- -t- Style terminal: disk not thickened : flowers small : leaves pinnate or 



ternate. 



w- Annual or biennial: leaflets incisely serrate, not white-tomentose : stamens 5 



to 20. 



3. P. Norvegica, L. Erect, stout, % to 2 feet high, at length dichoto- 

 mous above, hirsute: leaves ternate; leaflets obovate or oblong-lanceolate : cyme 

 leafy and rather loose: calyx large: stamens 15, rarely 20 : akenes rugose, or 

 nearly smooth : receptacle large, oblong. Throughout N. America, espe- 

 cially northward. 



4. P. rivalis, Nutt. More slender, usually diffusely branched : pubescence 

 softly-villous, sometimes nearly wanting : leaves pinnate, with 2 pairs of closely 

 approximate leaflets, or a single pair and the terminal leaf 3-parted ; upper 

 leaves ternate ; leaflets cuneate-ovate to -lanceolate, coarsely serrate : cymes 

 loose, less leafy : calyx small: petals minute: stamens 10 to 20 : akenes usually 



