116 MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA UNIVERSITY 
entire or incised. Leaves with short petioles, densely white silky-villous; leaflets 
crowded and often somewhat verticillate, about 1 em. long, broadly cuneate and deeply 
cut-toothed. Inflorescence dense in the typical form; flowers 1.5 em. in diameter. Hy- 
panthium silky-villous; bractlets oblong, generally much shorter than the triangular- 
ovate acute sepals. Petals obcordate, 6-10 mm. long, exceeding the calyx. 
Potentilla Breweri much resembles P. Plattensis. It has the large stipules character- 
istic of that species and also essentially the same flowers. The leaflets are, however, 
broader and less divided and densely silky-villous. In the typical form the cyme is 
rather dense and the flowers larger. 
California: Bolander, No. 5084, 1866; 1872: W. H. Brewer, Nos. 1708 and 1720, 
1863; Bolander & Kellogg, 1872; Baker & Nutting, 1894; Brandegee, 1892; A. Kellogg, 
1876; J. W. Congdon, 1890. 
Potentilla Breweri expansa Wats. 
Potentilla Breweri expansa Wats. Bot. Cal. 1: 179. 1876. 
Rydb. Bull. Torr. Bot. Club, 24: 1. 
Potentilla Plattensis leucophylla Greene, Erythea, 1: 4. 1898. 
InLustrations: Prater 52, f. 1; dissection of flower, f. 2; pistil, f. 3; stamen, f. 4; 
fruiting hypanthium and calyx, f. 5. 
Stems slender, decumbent or ascending; flowers smaller, on slender pedicels; leaves 
less villous, especially above; petals about 5 mm. long. 
This resembles P. Plattensis still more, having the open cyme of that species. It 
is apparently more common than the species. 
California: J. G. Lemmon, Nos. 64 and 712, 1874; No. 85, 1875: C.F. Sonne; 
No. 351, 1888; 1892 (P. Plattensis lewcophylla Greene); Coville & Funston, Nos. 1750, 
1531 and 2117, 1891; M. E. Jones, No. 351A, 1881. 
Nevada: 8S. Watson, No. 332, 1868 (in part). 
103. Potentilla ambigens Greene. 
Potentilla ambigens Greene, Erythea, 1: 4. 1893. 
Rydb. Bull. Torr. Bot. Club, 24: 3. 1897. 
ILLusTRATIONS: PLATE 58, f. 1; dissection of flower, f. 2; pistil, f 3; stamens, f. 4-5; 
fruiting hypanthium and calyx, f. 6. 
Stem stout, 6-7 dm. high, more or less striate, densely silky-villous with long 
spreading hairs, branched above. Stipules large, those of the basal leaves ovate-oblong, 
subentire, 2-4 cm. long, more or less membranous and brownish, those of the stem 
