ROSACEAE (koSE KAMILY) 



255 



n. 

 m. 



IV. 

 V. 



VI. 



Key to the Sections * 



Short-lived plants, mostly biennials I. 



Perennials. 



Leaves digitately 5-9-foliolate. 



Petioles without a remote reduced pair of leaflets; terminal 

 leaflet not petiolulate. 

 Depressed spreading perennials .... 

 Erect perennials, 1-several dm. high 

 Petioles with a remote reduced pair of leaflets or the termi- 

 nal leaflet petiolulate 



Leaves digitately 3-foliolate 



Leaves pinnate. 



Style short, not longer than the mature achene, glandular- 

 thickened below 



Styles long, exceeding the mature achene, filiform. 



Leiflets3-7 . . Vn. 



Leaflets 7-27. 



Green or greenish, never tomentose .... VIII. 



Whitish-silky or tomentose IX. 



I. SUPIHAEl^^Short-lived plants, mostly biennials; style short, 

 thickened-glandular below. 

 Leaves all pinnately 5- or more-foliolate; achenes with a lateral 



gibbosity Ic 



Some or all of the leaves trifoliolate. 



-- ■ Upper leaves trifoliolate; the lower pinnate. 



' Achenes with a lateral gibbosity; flowers axillary . . 2. 

 Achenes not gibbous; flowers in a leafy cyme ... 3. 

 ' ■ All the leaves trifoliolate. 



Stamens 10 or fewer; sepals exceeding the petals. 



Leaflets cuneate; flowers in a broadly branched cyme . ' . 4. 

 Leaflets broadly obovate; flowers in racemose cymules , 6. 

 Stamens more than 10; sepals and petals subequal . . 6. 

 n. CONCnOTAE. — Depressed-spi.iading perennials, digitately 5- 

 , ' foliolate; style short-filiform. 



Leaflets more or less deeply toothed all around . . . .7. 

 LekHets truncateiy 3-5-toothed at apex ..... 8. 

 m. GRACILES. — More or less erect perennials, digitately 5-9- 

 foliolate; style long and filiform. 

 Leaflets toothed or cleft halfway to the midrib, or less. 

 ' Leaves without white-tomentum. 

 Densely silky-villous at least below. 

 Tall erect plants, 3 or more dm. high. 



Cyme glomerate-congested, almost capitate . 

 Cyme coryinbosely broad-topped . 

 Low suberect plants, usually less than 3 dm. high , 

 Sparsely pubescent or glabrate, green. 



Low, subglaucous, sparsely villous plants, tisually less than 

 3 dm. high. 

 Leaflets subpinnate and somewhat dectutent . . 12. 



Leaflets strictly digitate 13. 



Tall, dark green, more or less hirsute plants, 3 dm. or more 



hi^h . . , 14. 



/i:t lieaveswhitertpmentose. 



Below only, green above 16. 



On both sides 16. 



' Leaflets toothed or cleft more than halfway to the midrib. 



Silky-sericeous; cyme crowded ...... 



White-tomentose below; cyme open and broad-topped 



IV. SUBJUGAE. — Rather low suberect perennials, having digitate 

 leaves with a pinnate tendeticy; style filiform. 



Leaves digitately 5-foliolate, witn a small additional pair on the 



petiole . .','"., . . . . . . 19. 



Leaves digitately 5-foliolate, the terminal leaflet petiolulate . 20. 



V. NIVEAE. — Low tufted perennials, digitately trifoliolate; style 



usually glandular-thickened' near the base. 

 Stem several-flowered; leaflets oblong-cuneate .... 21. 

 Stem 1-3-flowered; leaflets broadly obovate-rhomboid . . 22. 



VI. MULTIFIDAE. — Erect perennials; leaves pinnately 5-15- 

 foliolate; style glandular-thickened toward the base. 



Leaves silvery-white on both ,sides , 23. 



Leaves not silveryrWhite, at least not above.. 



Leaves silky-viUbus or subtomentose . - . . . 24. 

 Leaves neither silky-villous nor tomentose._ 



Somewhat hirsute, dark ^reen on both sides . . . 25. 



Obscurely pubescent and granulo-glandular . . . 26. 



SUPDfAE. 



COHCIHNAE. 

 GRACILES. 



SUBJUGAE. 

 NIVEAE. 



MULTIFIDAE. 



RUBRICAULES. 



MULTIJUGAE. 

 LEUCOPHYLLAE. 



P. paradoxa. 



9. 

 10. 

 11. 



P. Nicollettii. 

 P. rivalis. 



P. leucocarpa. 



P. biennis. 



P. monspeliensis. 



P. concinna. 

 P. bicrenata. 



P. glomerata. 

 P. viridescens. 

 P. diversifolia. 



P. decuirens. 

 P. glaucophylla. 



P. Nuttallii. 



17. 

 18. 



P. gracilis. 

 P. Candida. 



P. pectinisecta. 

 P. flabelUformis. 



P. subjuga. 



P. quinquefolia. 



P. nivea. 

 P. uniflora. 



P. pinnatifida. 



P. pennsylvanica. 



P. atrovirens. 

 P. virgulata. 



* Adapted from Dr. P. A. Rydberg's Monograph of the genus, 

 exhaustive work is gratefully acknowledged. — A. I«. 



Indebtedness to that 



