Part 4, 1908] ROSACEAE 
Leaflets serrate or dentate ; bractlets lanceolate or linear-lanceo- 
late, about equaling the sepals; stem at first ascending. 3 
Leaflets densely silky beneath ; those of the basal leaves cuneate- 
obovate, toothed only at the apex or at least only above the 
295 
. P. simplex. 
middle ; stem low, producing runners. 4. P. pumila. 
Pubescence of the stem, petioles, and peduncles spreading. 
Pubescence of the obovate or oblanceolate leaflets appressed. 5. PB. canadensis. 
Pubescence of the cuneate leaflets long and loosely spreading. 6. P. caroliniana, 
II. HETEROSEPALAE 
One species. 
“I 
III. SuPINAE 
Achenes with a corky gibbosity on the upper suture. 
. P, heterosepala, 
Leaves all pinnate with 3-5 pairs of leaflets; inflorescence cymose. 8. P. paradoxa, 
Lower leaves pinnate with 2-3 pairs, the upper ternate ; inflorescence 
falsely racemose. 
Achenes not gibbous. 
Lower leaves pinnate with 2 approximate pairs of leaflets, the upper 
ternate ; stem strict ; inflorescence cymose. 10 
Leaves all digitate ; the basal ones rarely pinnate in P. monspeliensis. 
Leaves ternate. 
Petals about half as long as the sepals ; achenes whitish, smooth ; 
hypanthium in fruit 5 mm. wide or less. 
Stem slender ; petals cuneate or obovate ; sepals and bractlets 
mm. long. 
Stem with diffuse, spreading branches; leaflets cuneate ; 
inflorescence cymose. 
wo 
. P. Nicolletit. 
. P. rivalis. 
Petals yellow ; stameris 10. ll. P. millegrana, 
Petals white ; stamens 5. (Mexican.) 12 
Stem with erect or strongly ascending branches ; inflores- 
cence inclined to be falsely racemose. 
Leaflets broadly obovate; plant decidedly glandular- 
puberulent; stamens about 10. 
Leaflets elliptic-obovate; plant densely pubescent but 
H 
ew 
not glandular ; stamens 20. 14. 
Stem stout; petals obcordate; sepals and bractlets 5 mm. 
. BP. michoacana. 
. P. biennis. 
P. flavovirens. 
long; plants densely glandular. 15. P. Kelseyt. 
Petals equaling the sepals or nearly so; hypanthium in fruit 
about 7 mm. wide ; stamens 15-20. 
Bractlets oval, usually obtuse; petals broadly obcordate; 
achenes smooth. 
Stem glabrous up to the inflorescence; petals with an 
open shallow notch. 16. P. flexuosa. 
Stem hirsute; petals with a narrow acute notch at the 
apex. 17 
Bractlets lance-elliptic or lanceolate, usually acute; petals 
obovate or cuneate, truncate or with a broad and shallow 
emargination ; achenes usually rugose when ripe. 18. 
Lower leaves digitately 5-foliolate, or ternate with the lateral 
leaflets 2-cleft to near the base; stamens 5. 
IV. ARENICOLAE 
One species. 20 
V. ARGENTEAE 
Leaves white-tomentose beneath. 5 
Teeth of the leaves ovate, margin not revolute; fruiting calyx 5-7 
mm. in diameter. . . 21 
Teeth of the leaves oblong or linear, margin revolute ; fruiting calyx E 
. £. leurocarpa. 
P. monspeliensis. 
19. P. pentandra, 
. P, Newberryt. 
. P. collina. 
5 mm. in diameter or less. 2. P. argentea, 
Leaves not white-tomentose beneath. 
Leaves green on both sides; leaflets of the basal leaves obovate or 
. P. intermedia. 
cuneate. 23 
Leaves grayish-silky and slightly tomentose beneath ; leaflets oblance- 
olate. 24. P. inclinata. 
VI. RECTAE 
Petals deep-yellow, only slightly longer than the sepals. 25. P. recta. 
Petals sulfur-yellow, half longer than the sepals. 26. P. sulphurea. 
VII. HEPTAPHYLLAE 
One Mexican species. 27 
VIII, NUTTALLIANAE 
Calyx and leaves more or less glandular-atomiferous ; whole plant 
yellowish- or brownish-green ; leaves with strong ribs. 
Leaflets dissected into linear or oblong divisions. 28. 
Leaflets coarsely toothed with lanceolate teeth. 29. 
. BP. leplophylla. 
P. brunnescens. 
P. Nuttall, 
