MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA UNIVERSITY 149 
Potentilla Muirii Greene, Pittonia, 1: 106. 1887. 
Greene, Fl. Fran. 1: 69. 
ILLUSTRATIONS: PLATE 90, f. 6; dissection of flower, f.7; stamen, f. 8; pistil, Vinee 
fruiting hypanthium and calyx, f. 10. 
Root perennial, deep, rather thick, crowned by an erect caudex 1-4 em. high, which is 
covered with the remains of old leaves. Stem 2—4 em. high, scapose, few-flowered, filiform, 
silky-villous. Basal leaves numerous, 2-3 em. long, densely white-silky, terete and worm- 
like from the very numerous minute, densely imbricated leaflets. Cyme few-flowered, sub- 
capitate. Hypanthium cupulate, 3 mm. in diameter, silky-villous; bractlets ovate, mi- 
nute, less than a fourth as long as the ovate sepals. Petals cuneate, shorter than the se pals. 
A very rare plant with leaves somewhat resembling those of Stellariopsis, but 
otherwise a typical member of the present group. It is only known from the type locality. 
California: (Summit of Mt. Hoffman) John Muir, 1872; J. M. Congdon, 1890. 
39. Horkelia Webberi (Gray). 
Ivesia Webberi Gray, Proc. Am. Acad. 10: 71. 1874. 
Brewer & Wats. Bot. Cal. 1: 183; Rattan, An. Key W. Coast Bot. 52. 
Potentilla Webberi Greene, Pittonia, 1: 105. 1887. 
Greene, Fl]. Fran. 1: 69. 
ILLUSTRATIONS: PLATE 88, f. 5; dissection of flower, f. 6; pistil, f. 7; stamen, f. 8; 
fruiting hypanthium and calyx, f. 9. 
Root deep, crowned with an erect, short scaly rootstock. Stems several, slender, 
short, less than 1 dm. long, nearly scapose, more or less tinged with brown, glabrate. 
Basal leaves 3-4 dm. long, many, pinnate, with 8-10 crowded pairs of leaflets, grayish 
silky, but not densely so; leaflets about 1 cm. long, divided to the base into linear or lan- 
ceolate acute segments; petiole with long fine silky hairs. Cyme subcapitate. Hypan- 
thium cupulate, tinged with brown, slightly silky, 4 mm. in diameter; bractlets linear or 
linear-lanceolate, shorter than the ovate or oyate-lanceolate sepals. Petals oblanceolate, 
yellow, scarcely equalling the sepals. 
H. Webberi differs somewhat in habit from the other members of the group. Its 
leaflets are comparatively few, the segments long, lanceolate or linear, acute, and resem- 
ble in form, size and pubescence somewhat those of H. unguiculata. ‘The inflorescence 
and flowers are, however, like those of the rest of the group, although the sepals are 
somewhat more elongated. It is a native of the Sierra Nevada. 
California: J. G. Lemmon, 1873; No. 69, 1874, and No. 93, 1895; Mrs. S. A. 
Plummer, 1879; Dr. Webber. 
Nevada: Collector not given. 
