PaRT 4, 1908] ROSACEAE 349: 
? Bootia sericea Raf. Aut. Bot. 169. 1840. 
Polentilla pennsylvanica bipinnatifida T. & G. Fl, N. Am. 1: 438, 1840. 
Potentilla candicans Fisch.; Lehm. Rev. Potent. 60, asasynonym. 1856. 
Stems several from a perennial root, erect or ascending, usually strict and simple, leafy, 
finely white silky-villous, 3-5 dm. high; basal leaves many, with petioles 5-10 cm. long, 
pinnate, with 7-9 approximate leaflets, densely and finely silky above, white-tomen- 
tose beneath ; leaflets 2-4 cm. long, obovate in outline, pectinately divided to near the mid- 
rib into almost linear, mostly obtuse segments; stem-leaves similar, but short-petioled or 
subsessile and often subdigitate ; stipules ovate or lanceolate, 24 cm. long, sometimes. 
toothed ; cyme dense and contracted; hypanthium white-silky, in fruit about 8 mm. in 
diameter ; bractlets oblong-lanceolate, shorter than the ovate sepals, which are 4-5 mm. 
long ; petals obovate, cuneate, truncate, about equaling or slightly exceeding the sepals; sta- 
mens about 20; pistils many ; styles short, glandular and thickened at the base. 
TYPE LOCALITY: Plains of the Saskatchewan. 
DISTRIBUTION : On the plains and hills from Manitoba and Minnesota to Colorado and Alberta. 
ILLUSTRATION: Mem. Dep. Bot. Columbia Univ. 2: 1.39, f. 1-5. 
168. Potentilla platyloba Rydb. Bull. Torrey 
Club 33: 143. 1906. 
Potentilla pulcherrima Rydb. Fl. Neb. 21: 16. 1895. Not P. pulcherrima Lehm. 1830. 
Potentilla bipinnatifida platyloba Rydb. Mem. Dep. Bot. Columbia Univ. 2: 100. 1898. 
Stout perennial; stems several, erect or ascending, 3-5 dm. high, pubescent with white 
appressed hairs; leaves pinnate, usually with but two pairs of leaflets; petioles of the basal 
leaves 4-7 cm. long, white-strigose; leaflets obovate, 2-6 cm. long, greenish and silky- 
strigose above, white-tomentose beneath, cleft into broad lanceolate or oblong divisions; 
stem-leaves short-petioled and often subdigitate; stipules large, ovate, 1.5-2 cm. long, 
often coarsely toothed; inflorescence narrow, with elongate erect branches, often flat- 
topped; hypanthium white-villous, deep, about 6 mm. broad in fruit; bractlets 4-5 mm. 
long, lanceolate or oblong, acute, nearly equaling the ovate acute sepals; petals about 
equaling the sepals, obovate; stamens 20; pistils numerous; styles short, thick and 
glandular at the base, : 
TYPE LOCALITY: Sheridan County, Nebraska. 
DISTRIBUTION : Plains, especially in sandy soil, from Hudson Bay to Colorado and Alberta. 
ILLUSTRATION: Mem. Dep. Bot. Columbia Univ. 2: pl. 39, f. 6-7. 
169. Potentilla virgulata A. Nelson, Bull. Torrey Club 
27: 265. 1900. 
Perennial, with a tap-root and short caudex ; stems 1 or 2, simple, erect, strict, 3-4 dm. 
high, slightly appressed-pubescent ; basal leaves pinnate, with 5-7 leaflets; petioles 6-10 
cm. long, sparingly appressed-hairy ; leaflets obovate in outline, 1-2 cm. long, green and 
sparingly appressed-silky above, grayish or white beneath, dissected into narrowly linear 
divisions with revolute margins; stem-leaves 5-foliolate, with more approximate leaflets, 
or the uppermost 3-foliolate ; stipules ovate-lanceolate, often acuminate ; cyme several- 
flowered, congested; hypanthium grayish-pubescent, in fruit 4 mm. broad ; bractlets linear, 
equaling the lanceolate sepals, 2-3 mm. long; petals small, orbicular, about 4 mm. long, 
slightly emarginate; stamens about 20; pistils numerous; styles short, glandular at the 
base. 
TYPE LOCALITY: Wet, grassy flat, near Mammoth Hot Springs, Wyoming. 
DISTRIBUTION : Wyoming and Utah to Alaska. 
170. Potentilla pectinata Raf. Aut. Bot. 164. 1840. 
Potentilla pennsylvanica A. Gray, Man. 122. 1848. Not P. pennsylvanica L. 1767. 
Potentilla Aiea Rydb. Bull. Torrey Club 23: 264. 1896. 
Perennial, with a short cespitose caudex ; stem decumbent or ascending, 2-4 dm. long, 
simple, slightly appressed silky-strigose; lower stipules lanceolate, scarious and brown, 
the upper ovate, green, more or less toothed; leaves pinnate, with 5 approximate 
leafiets, the lower pair the smaller, or subdigitately 5-foliolate, grayish-tomentose and 
