1g11] NELSON—IDAHO PLANTS : 265 
in cold bogs of the Northwest. It is always more or less pubescent, and its 
leaves are typically narrower and smaller. Its Idaho counterpart is a shrub 
of the mountains or foothills, in moist soil but not in marshy or wet places. 
S. idahoensis is reported plentiful throughout southern Idaho. 
The type is MACBRIDE 630, collected at Trinity, Elmore Co., August 23, 
IgIo. 
Potentilla trina, n. sp.—Perennial from a rough shreddy but 
slender vertical caudek, 4-8 cm. long, green and glabrate or even 
quite glabrous: stems less than 1 dm. high, slender but erect, few- 
leaved and few-flowered: leaves trifoliate: basal leaves on slender 
petioles 5-8 cm. long; leaflets short-petioled or subsessile, 1-3 cm. 
long, broadly obovate-cuneate, deeply and incisely toothed, the 
teeth more or less incised; stem leaves sessile, narrowly cuneate, 
incisely toothed at apex: cymes very few-flowered: calyx tube 
sparsely and minutely hirsute; sepals triangular-lanceolate, about 
5mm. long, acute, obscurely ciliolate; bractlets oblong, mostly 
obtuse, shorter than the sepals: petals obovate, emarginate, 6-8 
mm. long: stamens about 20: carpels 20-25. 
his is a very near relative of P. emarginata Pursh, and may be only a 
8eographical variety of that arctic species. If it stands as a species, it must do 
So on the strength of its almost glabrate condition, larger and longer rootstocks, 
larger leaflets, and erect habit. 
Collected by Macsrine in the Trinity Mountains, on the grassy banks of 
Star Lake, one of the Trinity Lakes, August 30, 1910, no. 680. Only a few 
plants were found. 
Prunus padifolia, n. comb.—Cerasus padifolia Greene, Proc. 
Biol. Soc. Wash. 18: 59. 1905. 
MAcBRIDE secured some excellent red cherry specimens on his collect- 
ing trip in Idaho in 1910. These led to an examination of GREENE’s interest- 
ing paper on “Some West American red cherries.” A checking up of the 
Specimens in the Rocky Mountain Herbarium in the light of this paper revealed 
Some sheets referable to the above name, including MACBRIDE 443 and 479 
from Silver City and Twilight Gulch. He secured two sets of specimens, 
one typically red-fruited, the other with fruit a clear lemon yellow. Otherwise 
no differences in the two collections could be seen. A character not mentioned 
y GREENE is the glandular denticulation of the leaf margin. 
Thermopsis xylorhiza, n. sp.—Stems clustered, erect, rather 
Slender, from a branched woody caudex surmounting a stout 
Woody root, 4~7 dm. high, simple and (at maturity) leafless below, 
sparingly branched above, glabrate and somewhat striate: green, 
