BY ae. “ 
Rosaceae 2 I 3 
AA. Lower leaves pinnate with 5 leaflets: upper leaves ternate; akenes not gibbous. E. 
P, rivalis Nutt. 
AAA. Leaves all ternate; akenes not gibbous. 
B. Calyx-tube in fruit 5 mm. or less wide; petals about YY as long as the sepals; 
stamens about 10. 
C. Stems with diffusely spreading branches; cymes rather wide, loose; leaflets 
oblanceolate. W.C.E. (P. leucocarpa. ) 
P. millegrana Engelm. (Diffuse 5-finger) 
CC. Stems with erect or strongly ascending branches; cymes narrow, elongated; 
leaflets obovate. W.C.E. (P. lateriflora.) 
P. biennis Gr. 
BB. Calyx-tube in fruit 6—8 mm. wide; petals about as long as the sepals; sta- 
mens lio 20." W. C. E; 
P. monspeliensis L. (Rough 5-finger) 
Subgenus ARENICOLAE—Biennial or perennial. Leaves pinnate; leaflets of 
basal leaves 721, dissected. Flowers small, white. Receptacle bristly. E. (P. new- 
berryi arenicola.) P. newberryi Rydb. 
Subgenus GRACILAE—Perennial, erect; stem in some retrorse-hirsute. Leaves 
digitately 5—9-foliolate or the upper ones, 3-foliolate, somewhat hairy; leaflets some- 
times divided to near mid-vein into narrow divisions, mostly obovate or oblanceolate. 
Flowers cymose, usually rather few. 
A. Leaflets toothed or cleft half way to the mid-vein or more. 
B. Stem-leaves few, with 3—5-leaflets. E. 
P. candida Rydb. 
BB. Stem-leaves several to many; mostly with 7 leaflets. E. (P. blaschkeana; P. 
longiloba.) P. flabelliformis . 
AA. Leaflets toothed less than half way to the mid-vein. 
C. Stem densely retrorse-hirsute. FE. 
FP. permollis Rydb. 
CC. Stem either not densely hairy or not retrorse-hirsute. 
D. Pubescence of the petioles spreading. 
E. Leaflets densely and finely white-tomentose beneath, nearly glabrous above. 
Wilgod ae F, gracilis Dougl. 
EE. Leaflets pubescent or hirsute but not tomentose beneath, somewhat pubescent 
above. E. (JP. dascia.) 
F. hallii Rydb. 
DD.  Pubescence of the petioles appressed or ascending. 
F. Leaves densely white tomentose beneath, appressed-silky but green above. E. 
P. dichrog, Rydb. 
FF, Leaves not white-tomentose beneath. 
G. Leaves densely silky-villous at least beneath. 
H. Cymes corymbosely flat-topped. E. 
P. viridescens Rydb. 
HH. Cymes in an almost head-like cluster. E. 
F. glomerata Nels. 
GG. Leaves pubescent or glabrate, green. 
I. Leaflets dissected at least half way to the mid-vein. 
J. Leaflets glabrous above, glabrous except on the veins beneath. E. 
F. glabrata Rydb. 
