ROSACEAE (ROSE FAMILY) 



255 



Key to the Sections * 



Short-lived plants, mostly biennials 



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. 



Leaflets 3-7 



Leaflets 7-27. 



Green or greenish, never tomentose .... 

 Whitish-silky or tomentose 



I. SUPINAE. 



II. CONCINNAE. 



III. GRACILES. 



IV. SUBTUGAE. 

 V. NIVEAE. 



VI. MULTIFIDAE. 

 VII. RUBRICAULES. 



VIII. MULTIJUGAE. 

 IX. LEUCOPHYLLAE. 



1. P. paradoxa. 



2. P. Nicollettii. 



3. P. rivalis. 



4. P. leucocarpa. 



5. P. biennis. 



6. P. monspeliensis. 



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



thickened-glandular below. 



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

 gibbosity .......... 



Some or all of the leaves trifoliolate. 



Upper leaves trifoliolate; the lower pinnate. 



Achenes with a lateral gibbosity; flowers axillary 

 Achenes not gibbous; flowers in a leafy cyme . 

 All the leaves trifoliolate. 



Stamens 10 or fewer; sepals exceeding the petals. 



Leaflets cuneate; flowers in a broadly branched cyme 

 Leaflets broadly obovate; flowers in racemose cymules 

 Stamens more than 10; sepals and petals subequal 



II. CONCINNAE. Depressed-spreading perennials, digitately 5- 



foliolate; style short-filiform. 



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



Leaflets truncately 3-5-toothed at apex 8. P. bicrenata. 



III. 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 corymbosely broad-topped ..... 

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

 Sparsely pubescent or glabrate, green. 



Low, subglaucous, sparsely villous plants, usually less than 



3 dm. high. 

 Leaflets subpinnate and somewhat decurrent 



Leaflets strictly digitate 



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



high 



Leaves white-tomentose. 



tHelow only, green above 15. P. gracilis. 

 On both sides 16. P. Candida. 

 Leaflets toothed or cleft more than halfway to the midrib. 

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

 White-tomentose below; cyme open and broad-topped 

 . SUBJUGAE. Kather low suberect perennials, having digitate 

 leaves with a pinnate tendency; style filiform. 

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

 petiole .......... 

 Leaves digitately 5-foliolate, the terminal leaflet petiolulate 

 NIVEAE. Low tufted perennials, digitately trifoliolate; style 

 usually glandular-thickened near the base. 

 Stem several-flowered; leaflets oblong-cuneate . . 

 Stern 1-3-flowered; leaflets broadly obovate-rhomboid 

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



foliolate; style glandular-thickened toward the base. 

 Leaves silvery-white on both sides ...... 



Leaves not silvery-white, at least not above. 



Leaves silky-villous or subtornentose 24. P. pennsylvanica. 



Leaves neither silky-villous nor tomentose. 



Somewhat hirsute, dark green on both sides . . .25. P. atrovirens. 

 Obscurely pubescent and granulo-glandular . . . 26. P. virgulata. 



9. P. glomerata. 



10. P. viridescens. 



11. P. diversifolia. 



12. P. decurrens. 



13. P. glaucophylla. 



14. P. Nuttallii. 



17. P. pectinisecta. 



18. P. flabelliformis. 



19. P. subjuga. 



20. P. quinquefolia. 



21. P. nivea. 



22. P. uniflora. 



23. P. pinnatinda. 



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

 exhaustive work is gratefully acknowledged. A. N. 



Indebtedness to that 



