260 ROSACEAE (ROSE FAMILY) 



beneath, with an obscure pubescence, petioled below, nearly sessile at summit; 

 leaflets obovate, dissected nearly to the midrib into linear segments which 

 are obscurely re volute-thickened ; the terminal leaflet petiolulate; stipules 

 ovate-lanceolate: flowers several, congested in a corymbose cyme: sepals 

 lightly pubescent, equaled by the bractlets and fully as long as the subor- 

 bicular petals. Marshy meadows, infrequent; Wyoming to the Dakotas. 



27. Potentilla saximontana Rydb. Bull. Torr. Bot. Club 23: 399. 1896. 

 Densely caespitose, with several silky pubescent stems only a few cm. long: 

 leaves numerous, mostly basal, pinnately 5-7-foliolate, silky-pubescent and 

 tomentose beneath; leaflets obovate, deeply incised; the oblong segments 

 obtuse or acute: flowers 1-3 on each scapose stem: calyx densely silky; the 

 bractlets oblong, obtuse, much shorter than the ovate triangular sepals: 

 petals broadly obcordate, much longer than the sepals: the style no longer 

 than the smooth achene. Alpine; in the mountains of Colorado. 



28. Potentilla rubricaulis Lehm. Stirp. Pug. 2: 11. 1830. Stems somewhat 

 tufted, ascending, about 1 dm. long, somewhat branched, silky-strigose : 

 leaves silky above, more or less white-tomentulose beneath, pinnately 5-7- 

 foliolate; leaflets small, obovate or oblong, deeply pinnatifid; the segments 

 narrowly oblong; stipules ovate, acute: flowers few, in an open cyme, with 

 erect branches: sepals silky, lanceolate, acute, longer than the oblong-linear 

 bracts and considerably exceeded by the obcordate petals. (P. minutiflora 

 Rydb. Bull. Torr. Bot. Club 23: 399. 1896 may be merely a depauperate 

 alpine form: P. tenerrima Rydb. 1. c. 398.) On the higher peaks of the Rocky 

 Mountains ; Colorado to Alberta. 



29. Potentilla plattensis Nutt. T. & G. Fl. N. A. 1: 439. 1840. Stems 

 several from the crown of a taproot, prostrate spreading or ascending, 1-2 dm. 

 long: leaves appressed-strigose or glabrate, pinnately 9-17-foliolate; leaflets 

 obovate-oblong, deeply incised; the lobes oblong, obtuse, or narrower and 

 acute; the stem leaves reduced, often merely 3-cleft; stipules broadly ovate, 

 large for the plant: flowers at first crowded, in age in an open paniculate cyme: 

 sepals strigose, twice as long as the similar bractlets but exceeded by the 

 obovate retuse petals. Frequent in grassy valleys; Colorado to Utah and 

 north to Wyoming and Montana. 



30. Potentilla pinnatisecta (Wats.) A. Nels. Wyo. Expt. Sta. Bull. 28: 104. 

 1896. Stems several, from the one or more scaly crowns of the woody tap- 

 root, erect, 10-15 cm. high, sparsely strigose: leaves nearly glabrous, some- 

 what hoary when young, mostly basal, pinnately many-foliolate; leaflets 

 crowded, deeply cleft into oblong obtuse lobes; stipules ovate-lanceolate, 

 acute: cymes small, 3-6-flowered: bractlets and sepals hirsute, lanceolate, 

 acute, unequal, shorter than the obcordate petals. Frequent in the alpine 

 regions of the Rocky Mountains; Colorado to British America. 



31. Potentilla monidensis A. Nels. Bull. Torr. Bot. Club 27: 266. 1900. 

 Stems numerous, from a multicipital caudex, prostrate-assurgent, slender, 

 silky-strigose, about 1 dm. long: leaves crowded on the crowns, petioled, 

 silky-strigose above, white with a dense hirsute silkiness beneath, pinnately 

 7-15-foliolate; leaflets crowded, pinnately or digitately cleft nearly to the mid- 

 rib into oblong-linear segments; stem leaves reduced, cleft into linear seg- 

 ments: sepals and bractlets silky-hirsute, lanceolate, unequal: petals broadly 

 elliptic or oval, exceeding the calyx. Infrequent; open sagebrush slopes; 

 Western Wyoming to Montana. 



32. Potentilla wyomingensis A. Nels. Bull. Torr. Bot. Club 27: 32. 1900. 

 Stems crowded on the multicipital caespitose caudex, simple except for tho 

 corymbosely branched open cyme, green, glabrate, less than 2 dm. high: 

 leaves mostly basal, 5-7-foliolate, green on both sides, nearly glabrous above, 

 lightly pubescent beneath ; leaflets obovate to oblanceolate, coarsely and deeply 

 serrate; stipules lanceolate, entire, acute: sepals hirsute, ovate-lanceolate, 

 twice as long as tlie oblong-linear bractlets: petals broadly obovate, retusely 

 truncate at summit. Subalpine; mountains of central Wyoming to Yellow- 

 stone Park and Montana. 



33. Potentilla rupicola Osterh. Bull. Torr. Bot. Club 26: 256. 1899. Stems 



