556 PROCEEDINGS OF THE AMERICAN ACADEMY 



leaves appressed silky-villous ; stipules broad, mostly incised ; leaflets 

 7-13, nearly uniform in size, 3-6" long, broadly cuneate, deeply in- 

 cised; cymes mostly crowded; flowers rather large, the emarginate 

 petals 3 - 5" long, much exceeding the calyx ; carpels 20 - 25, on vil- 

 lous pedicels, the receptacle and disk hairy. — Mono Pass in the 

 Sierra (1720 Brewer) ; summit above Cisco (Bolander). 



13. P. Plattensis,- Nutt. Subalpine ; pubescence throughout ap- 

 pressed silky-villous, scanty or nearly wanting ; stems decumbent, slen- 

 der, 3 - 12' long ; stipules linear-lanceolate to oblong, mostly entire; 

 leaflets 7-13, usually crowded and often alternate, 2-6" long, ovate, 

 deeply incised-pinnatifid into 3-7 linear segments ; flowers few, on 

 slender pedicels, in an open cyme ; petal 2 - 3" long, usually exceeding 

 the calyx, obovate and entire or retuse, or obcordate ; carpels 25 - 40. 



Eocky Mts. of Colorado. P. diversifolia, var. pinnatisecta, Watson 



(331 and 332), from the Clover Mts., Nevada, and the Uintas, must 

 probably be referred here, though more densely silky, and the hairs 

 upon the calyx spreading. 



14. P. dissecta, Pursh. (P. diversifolia, P. Drummondii, and 

 P. rubricaulis, Lehm.) Low, alpine, more or less silky-villous, with 

 somewhat spreading hairs, or nearly glabrous ; stems decumbent or 

 ascending, 3-12' long ; stipules ovate- or oblong-lanceolate, entire ; 

 leaflets 5 - 7, or rarely but three, often glaucous, closely pinnate, or as 

 frequently digitate, the upper one V long or less, cuneate-oblong, 

 incisely pinnatifid or serrate, the lowest often but trifid, the segments 

 acute or acutish, and more or less tufted with white hairs ; flowers few, 

 on slender pedicels in an open cyme ; calyx more or less villous with 

 spreading hairs, the bractlets short, the lanceolate sepals shorter than 

 the petals, which are 2 - 4" long, obovate and retuse or obcordate ; 

 receptacle very villous; carpels 10-20, or more. — From British 

 America to Colorado and California. 



An examination of the original specimen of P. dissecta from " Hud- 

 son's Bay " in Herb. Banks (kindly made by Mr. Trimen of the 

 British Museum) shows that it is but one of the several forms that 

 have been referred to P. diversifolia, " from which it seems only to 

 differ in its larger size, less amount of hairiness (the under side of the 

 leaves only slightly pilose), and more deeply cut leaflets." Pursh's 

 name must be retained as the oldest. A quite variable species, but 

 strongly marked. The frequent form with nearly glabrous leaves is 

 var. glaucophtlla, Lehm. A rather stout and glabrous form with 



