Parr 4, 1908] ROSACEAH 301 
Leaflets not dissected to near the midrib. 
Leaflets not densely grayish-strigose. 
Leaflets 5-17. 
Stem villous with spreading hairs. (Mexican.) 155. P. Richardit. 
Stem not villous with spreading hairs. (United States.) 
Sepals ovate or lance-ovate ; bractlets lanceolate or 
oblong. 
Stem about 1 dm. high; leaflets 1 em. long or less, 
toothed only at the apex. 52. P. decurrens. 
Stem 2-4 dm. high; leaflets over 1 cm. long; if 
smaller, then deeply cleft. 
Leaflets less than 2 cm. long; calyx silky-strigose. 156. P. cascadensis. 
Leaflets over 2 cm. long ; calyx hirsute. 157. P. Drummondii. 
Sepals linear-lanceolate, acuminate ; bractlets linear- 
subulate. 134. P. rupincola. 
Leaflets 17-27. | 158. P. multijuga. 
Leaves densely grayish-strigose or silky. 
Stem 144 dm. high ; leaflets cuneate or linear-oblong, toothed 
at the apex only. 
Stem ascending or decumbent ; leaves conduplicate ; pistils 
numerous. . £. crinita. 
Stem erect ; leaves flat; pistils 5-12. 160. P. Lemmonii. 
Stem stout, 6-7 dm. high; leaflets obovate-oblong, coarsely 
serrate. 142. P. ambigens. 
XXXI. MULTIFIDAE 
Pubescence of the under side of the leaves silvery-white. 
cay and the lower part of the stem silky-villous with spreading 
airs 
Terminal leaflet of the basal leaves 5-9-toothed ; the lateral ones 
2-5-toothed. (Arctic species.) 
Leaflets greener above, their lobes oblong, elliptic or lanceo- 
late, mostly obtuse ; terminal leaflet stalked. 
Plant 5 cm. high or less; leaves glabrate above; petals 
usually entire. 161. P. Sommerfeltit. 
Plant 5-30 em. high ; leaves long-hairy above ; petals usu- 
ally emarginate. 162. P. subarctica. 
Leaflets nearly equally grayish-silky on both sides, their lobes 
linear-lanceolate, acute ; terminal leaflet usually sessile. 163. P. pulchella. 
Terminal leaflet of the basal leaves 11-15-toothed ; the lateral ones 
5-9-toothed. (Great Basin species.) , paucijuga. 
Petioles and stem tomentulose and silky-strigose. 
Segments of the leaflets acute ; styles not thickened. 165. P. multifida. 
Segments of the leaflets obtuse ; styles thickened at the base. 
Segments of the leaflets linear or linear-oblong ; branches of 
the inflorescence usually short and ascending. 
Leaflets usually white on both sides; petals and sepals 46 
mim. long. 
Stem decumbent or ascending, 0.5-1 dm. high; leaflets . 
2 or 3 rather approximate pairs. 166. P. pseudosericea.. 
Stem erect, 3-5 dm. high ; leaflets 3-7 usually rather re- ; 
mote pairs. 167. P. bipinnatifida. 
Leaflets green above ; petals and sepals about 3mm. long. 169. P. virgulala. 
Segments of the leaflets lanceolate or oblong, usually green 
above ; branches of the inflorescence long and erect. 168, P. platyloba. 
Pubescence of the under side of the leaves grayish. 
Petioles and stem appressed-pubescent. 
Segments of the leaflets narrowly linear ; petals and sepals about 3 : 
mim. long. . P. virgulata. 
Segments of the leaflets ovate, lanceolate, or oblong ; petals and 
sepals +6 mm. long. ; . 
Basal leaf-blades orbicular or pentagonal in outline with 3 ap- . 
proximate pairs of leaflets. 170. P. pectinata. 
Basal leaf-blades obovate in outline; leaflets usually more 
than 3 pairs and more distant. . . 
Leaves glandular-pruinose above and sometimes with scat- 
tered long hairs. 
Leaves short-strigose above. 
Margins of the leaf-segments not revolute. 
Margins of the leaf-segments revolute. 
Petioles and stem with spreading hairs. 
Flowers distinctly pedicelled ; upper leaflets of the basal leaves 
with 9-13 segments; pubescence of the stem and petioles 
long. 
Plant dark-green ; leaves scarcely paler beneath. 
Plant not dark-green ; leaves decidedly paler beneath. 
Flowers usually subsessile, densely conglomerate ; upper leaflets 
of the basal leaves with 15-21 segments ; pubescence of the stem 
short and dense. 
171 
174, 
175 
176 
172. 
173. 
. BP. glabrella. 
P. pennsylvanica. 
P. avrachnoidea, 
. P. atrovirens. 
. BP. strigosa. 
P. lasiodonia. 
