192 ROSACEAE 



Locs. — Wcstfalls Mdw., Yosemitc, Bolander 4964 ; Clover Mdw., Soquel Eange, Madera Co., 

 Kenned;/; Jackass Mdws., Madera Co., Congdon; Iluntinpton Lake, Jepson 13,044; Vermilion 

 Vallcv, Mono Creek, Fresno Co., Jepson 13,189; Markwood Mdws., Fresno Co., Jepson 16,028; 

 Inyo Co. (Pitt. 1:103). 



Refs. — PoTKNTiLLA UNQUICULATA Greene, Pitt. 1:105 (1887); Jepson, Man. 490 (1925). 

 Ivesia unguiculata Gray, Proc. Am. Acad. 7:339 (1868), type loc. Wcstfalls Mdw., Mariposa Co., 

 Bolander -1904. Horkdia nnguiculcita Rydb. Mem. Dept. Bot. Columbia Univ. 2:146, pi. 87 (1898). 

 P. ciliata Greene, Pitt. 1:103 (1887), type loc. "Owens Valley," Inyo Co., Kellogg. 



27. P. pickeringii Greene. Silk Ivesia. Steins erect or spreading, % to 2 

 feet higli ; herbage white silky-villous ; leaves pinnate, the basal numerous, with 

 blades 3 to 10 V^ inches long, the petioles about l^ to 1/5 as long; cauline leaves 5 to 

 10, 1 to 2 (or 3 1/2 ) inches long; leaflets numerous, at first congested and closely 

 imbricated, 2 to 5-parted, 2 to 6 lines long, the segments oblong to oblong-elliptic; 

 cyme freely branched, the flowers in dense or capitate terminal clusters; flowers 

 4 to 5V^ lines wide ; calyx-tube turbinate at base ; petals white or yellowish, roundish- 

 obovate, truncate or emarginate-mucronate, tapering to a narrow claw, 2 to 3 lines 

 long, exceeding the calyx-lobes; stamens 14 to 20; filaments filiform; achenes 2 to 5. 



Dry gravelly soil in valleys, 5000 to 5500 feet: Sierra Nevada (east or north 

 side) from Nevada Co. to Siskiyou Co. Southern Oregon; western Nevada. June- 

 Aug. 



Field note. — The root-crown becomes oblong or subglobose through the continued addition 

 of the persistent leaf bases. 



Locs. — Dog Valley, Nevada Co., Sonne; Martis Valley, Nevada Co., Sonne 353; Sierra 

 Valley, Plumas Co., Jepson 8034; Portola, Plumas Co., K. Brandegee ; Edgewood, Siskiyou Co., 

 T. Brandegee. 



Eefs. — PoTENTiLLA PICKERINGII Greene, Pitt. 1:105 (1887); Jepson, Man. 491, fig. 486 

 (1925). Ivesia picTceringii Torr. Phanerogamia of Pac. Coast, Wilkes Exped. 288, t. 4 (1874), 

 type loc. Klamath Eiver, Piclcering. Horlcelia picTceringii Eydb. Mem. Dept. Bot. Columbia Univ. 

 2:145, pi. 86 (1898). H. sericoleuca Eydb. I.e. 144, pi. 85, figs. 1-5, type loc. Sierra Co., Lemmon 

 11 (differing mainly in the more robust habit and slightly longer pedicels). Ivesia sericoleuca 

 Eydb. N. Am. Fl. 22:284 (1908). 



28. P. argjrrocoma Jepson. Mountain Mouse-tail. Stems spreading, 4 to 

 10 inches high, villous-pubescent or glabrate; basal leaves many, the blades 1 to 

 2y2 inches long, on petioles ^^ to % inch long; cauline leaves 1 or 2, the blades 1 

 inch long ; leaflets densely silvery-silky, densely imbricated, 2 to 3-parted, the seg- 

 ments oblong-elliptic, 1 line long ; cyme open or somewhat dense, its forks ending 

 in subcapitate clusters; flowers 4 lines wide; calyx-tube rusty, white-hirsute within; 

 bractlets oblong-lanceolate, half as long as the lanceolate calyx-lobes; petals white, 

 obovate- or cuneate-spatulate, often short-clawed, 2 lines long, exceeding the calyx- 

 lobes; stamens 20; filaments somewhat dilated; achenes 4 to 7, smooth. 



Dry open or coniferous slopes, 6000 to 6900 feet : San Bernardino Mts. May- 

 June. 



Loc. — Potentilla argyrocoma is an extremely narrow endemic, having been collected only in 

 Bear Valley of the San Bernardino Mts. (Parish 2362). 



Eefs. — Potentilla argyrocoma Jepson, Man. 491 (Apr. 14, 1925) ; M. & J. Bull. S. Cal. 

 Acad. 24:13 (May 20, 1925). Horl-elia argyrocoma Eydb. Mem. Dept. Bot. Columbia Univ. 

 2:144, pi. 84 (1898), type loc. San Bernardino Mts., Parish 151. Ivesia argyrocoma Eydb. N. 

 Am. Fl. 22:284 (1908). I. unguiculata Wats. Bot. Cal. 2:444 (1880), not Gray. 



29. P. santolinoides Greene. Silver Mouse-tail. Plants 1/2 to 1 foot high, 

 the stems slender, erect, nearly naked, subglabrous, diffusely branched above and 

 forming an open panicle of cymes; leaves numerous, pinnate, the blades terete, 

 densely silvery- villous, 1 to 2^/2 (or 5) inches long, the petioles 3 to 5 lines long, 

 the minute leaflets closely imbricated and all but concealed by the pubescence; 

 panicle large; pedicels filiform, 2 to 9 lines long; flowers 3^2 to 4 lines wide; petals 

 white, orbicular, exceeding the short calyx-lobes; stamens 14 to 16; filaments fili- 

 form; anthers didymous, purple or pale, opening by a subterminal slit or pore; 

 pistil 1 ; achenes smooth or faintly sinuous-rugulose. 



