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Rosaceae 215 
Subgenus PE OCORH YLLAE=-Perential..leaves pinnate; leaflets 5—-13, gray- 
ish or whitish-silky or villous or tomentose specially beneath, coarsely toothed but not dis- 
sected. E., P. bruceae Rydb. 
Subgenus MULTIJUGAE—Perennial; stem erect to prostrate, usually less than 
3 dm. high (except P. drummondii). Leaves hirsute or strigose, not tomentose, pinnate; 
leaflets 7—27 (in P. drummondii sometimes only 3 or 5), coarsely toothed or dissected. 
A. Stems diffuse or spreading; pedicels arcuate-spreading at least in fruit. C. E. 
P. klamathensis Rydb. 
AA. Stems erect or ascending; pedicels erect or ascending, straight. 
B. Leaflets dissected to near the mid-vein. 
C. Stem sparingly appressed-silky; basal leaves with 15——25 leaflets; sepals acute. 
Ey P. versicolor Rydb. 
CC. Stem glabrous up to the inflorescence; basal leaves with 11—13 leaflets ; 
sepals acute. E. P. decurrens Rydb. 
CCC. Stem strigose; basal leaves with 7—19 leaflets; sepals acuminate. E. 
P. wyomingensis Nels. 
BB. Leaflets not dissected to near the mid-vein. 
D. Leaflets of basal leaves 12 cm. long; calyx silky-hairy. W. C. 
P. cascadensis Rydb. 
DD. Leaflets of basal leaves | cm. or less long; calyx stiff-hairy. (See CC.) 
DDD. Leaflets of basal leaves 2—6 cm. long; calyx stiff-hairy. C. 
P. drummondii Lehm. 
ARGENTINA SILVER-WEED 
Herbs, perennial, with long runners. Leaves interrupted-pinnate; leaflets many. 
Flowers solitary, on long peduncles, in the axils of the basal leaves. Calyx-cup almost 
flat; segments usually 5 but often more. Petals yellow, broadly elliptic or almost orbic- 
ular, not at all clawed, obtuse, scarcely emarginate. Stamens 20—25, in 3 series, near 
base of calyx. Receptacle hemispheric. Pistils very many; style lateral, attached almost 
at the middle of the ovary, glabrous. (L. argentina—of silver; from the silvery-hairy 
leaves. ) 
A. Leaves silvery on both sides. W.C. E. (A. anserina concolor.) 
A. argentea Rydb. 
AA. Leaves silvery beneath, green above. . . 
B. Stem and petiole and leaf-rachis densely hairy. W.E. (Potentilla anserina.) 
A. anserina Rydb. (Goose Tansy) 
BB. Stem and Batol and leaf-rachis glabrous or slightly appressed-hairy. W. 
(Potentilla pacifica; A. occidentalis.) 
A. pacifica Rydb. 
COMARUM 
Herb, perennial, stout, dark-green, nearly glabrous; rhizome creeping. Leaves 
alternate, pinnate; leaflets 5-7; stipules large. Flowers in cymes, large. Calyx-cup 
flat; segments 5. Petals 5, shorter than the calyx-segments, acute, purple. Stamens 
numerous, on the large pubescent calyx-cup. Pistils many; style lateral. Receptacle 
pubescent, becoming spongy in fruit. Akene glabrous. (Gk. komaros=the Arbutus, 
from the resemblance of the fruits.) W. E. 
C. palustre L. (Purple Marsh-locks) 
