72 
BOTANY. 
Potentilla anserina, Linn. Sp. 1 ,p. 495; Torr. (kGray, Flor. 1, p. 444. Shores of Klamath 
lake, 0. T. 
Potentilla flabellifolia, Hook.; Torr. & Gray, Flor. p. 442. Cascade mountains, 0. T. ; 
altitude 6,000 feet. 
Potentilla gracilis, var. flabelliformis, Torr. & Gray, Flor. p. 440. McCumher’s, N. Cali¬ 
fornia, and Klamath basin. 
Potentilla rigida, Nutt, in Jour. Acad. Philad. 7, p. 20. Banks of Hat creek, N. California. 
Potentilla glandulosa, Lindl. Bot. Reg. t. 1583 ; Hook & Am. Bot. Beech., p. 338. Banks 
of Hat creek, N. California. 
IVESIA, Nov. Gen. (Torr. & Gray.) 
“ Calyx 5-fidus et 5-bracteolatus, tubo concavo vel campanulato. Petala 5, oblongo-cuneata 
vel obcordata, decidua. Stamina 20, bi-triseriata, tubo calycis, vel tantum 5 margini disci 
tenuis, inserta; filamenta filiformia vel subulato-filiformia, persistentia. Ovaria plura vel 
plurima, receptaculo conico villoso insidentia : ovulo pendulo : stylus infra-apicalis, gracilis, 
articulatione deciduus: stigma simplex. Achenia lmvia. Radicula supera. Herbm Horkelias 
facie, plurifoliolatge, albi florm, in sectionibus 2 disponendm, nempe:— 
<£ §1. Horkelioides. Perennes, e caudice crasso confertissime multifoliolatm ; floribus con- 
gestis subsessilibus ; calycis 5-fidi tubo campanulato vel turbinato; petalis spathulatis parvulis ; 
acheniis lmvibus paucis (ovariis 6-12?) Species duo: I. Gordoni, (Horkelia Gordoni, Hook. 
Kew. Jour. Bot. 5, p. 341, t. 12, H. ? multifoliolata, Torr. in Sitgreaves, Zuhi Exped.p. 159.) 
I. Pickeringii, N. California ; Coll. Expl. Exped. 
“ § 2. Potentilloides. Annum, laxe plurifoliolatm, laxiflorm, pedunculis ebracteatis ; calyce 
concavo (bracteolis conformibus) subsequaliter fere 10-partito ; acheniis plurimis grosse pauci- 
costatis. Sp. 1, nempe: 
“I. gracilis, (sp. nov.) : gracilis, laxe villosa ; foliis radicalibus 11-21-foliolatis; foliolis infe- 
rioribus 3-5-partitis breviter petiolulatis, summis plerumque alte bifidis subconfluentibus, 
segmentis lineari seu oblongo-spathulatis, caulinis parvis cum foliolis 5-9 subintegris ; floribus 
parvis in cyma effusa sparsis; pedunculis ebracteatis filiformibus mox cernuis; petalis 
obcordatis calyce longioribus; stylis inferne vesiculoso-subincrassatis.—Banks of Rhett lake, 
one of the Klamath group. A foot high, producing many slender and nearly erect stems from 
a slender and evidently annual-root. Leaflets thin, 3 to 6 lines long, irregular, often alternate, 
the lower ones rather sparse. Branches of the open cyme, as well as the peduncles, very 
slender ; the latter fully an inch long. Flowers very small; the calyx, when spread out flat, 
only about 4 lines wide, flattish, and open like that of a Potentilla; the accessory lobes like 
the real sepals, only slightly smaller and blunter. Petals white, broad, deciduous. Stamens 
20, in three ranks, five of them, viz : those opposite the true sepals inserted on the margin of a 
narrow and thin patelliform perigynous disk, (which is villous, like the receptacle it surrounds,) 
the others borne on the face of the calyx, the five opposite the petals inserted very close to the 
disk, but distinguisliably separate from it; the remaining ten inserted higher up, just below 
the 10 sinuses, and answering to them, but in reality borne one on each side of the base of each 
interior or true division of the calyx ; the persistent filaments slightly dilated at the base. 
Receptacle conical, hirsute. Ovaries indefinite, 30 or more, inserted by the inner angle just 
above the base ; the style inserted a little below the rounded apex by a narrow base, above 
which it is more or less enlarged and glandular, or rather vesicular, and tapering gradually to 
