POSACEAE. 505 



II. Potentilla leucocarpa Rydb. Diffuse Cinquefoil. (I. F. f. 1924.) 

 )ecumbent or ascending, annual, usually diffusely branched, 4-8 dm, high, softly 

 illous-pubescent, or glabrate. Leaves all but the uppermost petioled, 3-foliolate; 

 >aflets oblong, cuneate, thin, flaccid, pubescent, deeply serrate, 2-4 cm. long; 

 pwers loosely cymose, 3-4 mm. broad; calyx-lobes ovate, acute, exceeding the 

 bovate petals; stamens about 10; style slightly thickened below. In damp soil, 

 11. to Minn., N. Mex.. Cal. and Wash. May-Sept. 



Potentilla rivalis Xutt., a western species which may reach our limits, is distin- 

 uished from this by its usually pinnately 5-foliolate lower leaves, viscid pubescence, 

 tricter erect habit, and more numerous stamens. It has been collected at the stockyards 

 f Chicago. 



12 Potentilla paradoxa Nutt. Bushy Cinquefoil. (I. F. f. 1925.) 

 Softly pubescent, annual or biennial, rather stout, bushy, 3-8 dm. high. Leaves 

 11 but the uppermost petioled, pinnately 7-11-foliolate; leaflets obovate or oval, 

 ibtuse. 15-25 mm. long, sparingly pubescent, crenate, the upper ones commonly 

 onfluent or decurrent on the rachis; flowers terminal, loosely cymose, leafy - 

 >racted, 7 mm. broad; petals obovate, cuneate, about equalling the ovate calyx- 

 obes; stamens about 20; style terminal, thickened below. Shores and river banks, 

 S. Y. and Ont. to Ore. and N. Mex. Also in Mex. and Mantchuria. June-Sept. 



13. Potentilla Nicolletii (S. Wats.) Sheldon. Nicollet's Cinquefoil. 

 I. F. f. 1926.) Similar to /'. paradoxa, but more spreading and more branched; 

 ower leaves only pinnate, with few leaflets; upper leaves 3-foliolate; teeth of the 

 eaflets acute; inflorescence elongated, falsely racemose; stamens 10-15. N. Dak., 

 owa and Mo. 



14. Potentilla Hippiana Lehm. Woolly Cinquefoil. (I. F. f. 1927.) 

 Perennial, 3-5 dm. high, densely floccose as well as silky. Lower and basal leaves 

 jetioled, pinnately 5-11-foliolate; leaflets oblanceolate or oblong, obtuse, 2-5 cm. 

 long, deeply toothed, very white beneath, the lower ones smaller than the upper; 

 lowers loosely cymose, 7-10 mm. broad; petals obovate, refuse, a little exceeding 

 he lanceolate acute calyx-lobes; stamens about 20. Dry soil, Minn, and Assin. to 

 Br. Col., Neb. and N. Mex. June-Aug. 



T5. Potentilla effusa Dougl. Branched Cinquefoil. (I. F. f. 1928.) 

 Closely related to P. Hippiana. Plant 2-4 dm high, diffusely branched above ; 

 leaves sometimes interruptedly pinnate, tomentose-canescent, but not silky; leaf- 

 lets 5-1 1, cuneate-oblong, obtuse; flowers 6-8 mm. broad, loosely cymose; bract- 

 lets shorter than the lanceolate acute calyx-lobes; petals obovate, emarginate, ex- 

 ceeding the calyx-lobes; stamens about 20. Prairies, Minn, (according to^Upham) 

 to Mont, and Colo. Summer. 



16. Potentilla bipinnatifida Dougl. Cut-leayed Cinquefoil. Stems 

 erect or ascending, simple, white silky-villous, 3-5 dm. high. Basal leaves pin- 

 nately 7-9-foliolate; stem-leaves subsessile and often subdigitate; leaflets approxi- 

 mate, obovate in outline, pectinately divided into linear obtuse segments, silvery 

 white; flowers densely cymose; sepals ovate, longer than the lanceolate bractlets 

 md about equalling the obovate-cuneate, truncate petals. Prairies, Hudson Bay 

 oSask., Alb. and Colo. [P. Pennsylvanica bipinnatifida T. & G.] 



17. Potentilla atrovirens Rydb. Dark-green Cinquefoil. Stem stout, 

 3 dm. high, branched, with erect branches, dark green, densely pilose. Leaves 



imilar to those of P. Pennsy 'foam : ca, but dark green, densely pilose and strongly 

 reined; cyme many-flowered, narrow, with erect branches ; bractlets and sepals 

 >vate. subequal, exceeding the cuneate-obovate bright yellow petals. Prairies. 

 finn., S. Dak. and Wyo. 



18. Potentilla Pennsylvanica L. Prairie Cinquefoil. (I. F. f. 1929.) 

 item 4-8 dm. high, tomentose. Leaves pinnately 5-1 5-foliolate, grayish-tomentose 

 leneath. glabrous above ; leaflets oblong or oblanceolate, cleft halfway to the mid- 

 ib into oblong lobes, margins scarcely revolute ; cymes dense; petals yellow, 

 bovate, truncate or slightly emarginate, about equalling the ovate triangular 

 cute sepals and the lanceolate bractlets ; style thickened below. On prairies, 

 ludson Bay to the Canadian Rocky Mountains, south to N. Mex. Summer. 



Potentilla Pennsylvanica strigosa Pursh. Stem usually lower; pubescent with long 

 illous hairs-, leaflets with deep narrow divisions, margins revolute. Manitoba and the 

 1. W. Terr, to Kans. and N. Mex. Also in Siberia. 



