ROSACES. (ROSE FAMILY.) 85 



10. P. Plattensis, Nutt. Subalpine: pubescence appressed silky-villous 

 throughout, scant ij or nearly wanting: steins decumbent: leaflets 7 to 13, usually 

 crowded and often alternate, deeply incised -pinnat/Jid into 3 to 7 linear segments : 

 flowers few, in an open cyme : carpels 25 to 40. Torr. & Gray, Fl. i. 439. 

 P. diversifolia, var. pinnatisecta of Bot. King's Exp. 87. Mountains of Colo- 

 rado and Nevada, and in the Uintas. 



11. P. dissecta, Pursh. Low, alpine, more or less silky-villous, with some- 

 what spreading hairs, or nearly glabrous : stems decumbent or ascending : leaflets 

 5 to 7, or rarely but 3, often glaucous, closely pinnate, or as frequently digitate, 

 the upper one incisely pinnatifid or serrate, the lowest often but trifid: flowers few, 

 in an open cyme : carpels 10 to 20 or more. P. diversifolia, Lehm. From 

 Colorado to California and British America. The following varieties occur 

 with the type. 



Yar. glaiicophylla, Lehm. Glaucous-green: leaves digitate, nearly gla- 

 brous on both sides. 



Var. milltisecta, Watson. Canescent with a not very dense silky pubes- 

 cence : leaves digitate or nearly so, the leaflets digitately or pinnately divided 

 and the segments linear. Bot. King's Exp. 86. 



Var. (?) decurrens, Watson. Leaflets but 3 or with 1 to 2 additional 

 distant pairs of smaller ones, the terminal leaflet truncately 3-toothed, the upper 

 pair 2 to 3-toothed, conspicuously decurrent : stem \-flowered, 3 inches high, gla- 

 brous throughout, excepting the villous calyx and tufted apices of the leaves. 

 Eev. Pot. 557. From peaks of the Uiutas. 



M- -w- Leaves digitately 5 to 1-foliolate (rarely pinnate in No. 12) : tomentose or 



villous. 



12. P. gracilis, Dougl. Villous and more or less tomentose: stems 2 to 3 

 feet high: leaflets mostly 1, incisely serrate or pinnatifid, tomentose beneath, 

 green above and subvillous or appressed silky: carpels 40 or more. From 

 New Mexico to Utah and California, and thence northward to the Saskatche- 

 wan and Alaska. 



Var. flabelliformis, Torr. & Gray. Leaflets very deeply pinnatifid. 

 Fl. i. 440. 



Var. fastigiata, Watson. Cyme shorter and more compact, more densely 

 pubescent : often low. Rev. Pot. 557. P. fastigiata, Nutt. 



Var. rigida, Watson. Villous, but without tomentum : usually tall and stout. 



Loc. cit. P. Nuttallii, Lehm. 



13. P. humifusa, Nutt. Densely white-tomentose and silky-villous: stems 

 decumbent, 2 to 4 inches long, slender : leaflets 5, green and appressed silky 

 above, only the rounded or truncate apex serrate with 3 to 5 teeth : carpels 15 to 20. 



From the mountains of Colorado to the Saskatchewan. 



*H- -M- -M. Leaves ternate : low, arctic or alpine, few-flowered. 



14. P. nivea, L. Pubescence silky-villous, densely white-tomentose on 

 the under side of the leaves : leaflets coarsely incised-serrate or pinnatifid, the 

 terminal one sessile or petiolulate : carpels few or many. From Colorado 

 northward. 



Var. dissecta, Watson. Leaves digitately or pinnately 5-foliolate, the 

 leaflets deeply pinnatifid : stems 1 to 2 inches high, 1 to 3-flowered. Rev. 

 Pot. 559. In the Uintas and mountains of Montana and British America. 



