ROSACEAE 



379 



22. Rosa [Tourn.] L.* 



Styles much exserted, about equalling the stamens. 



Leaflets glabrous or slightly pubescent on the veins beneath, 



dark green and shining above. 

 Leaflets velutinous-pubescent, beneath, rather dull above. 

 Styles not exserted or only slightly so. 



Sepals reflexed after flowering and early deciduous. 



Achenes inserted both on the inner walls of the hypan- 

 thium and in the bottom; prickles rarely in- 

 frastipular. 

 Leaflets 3-5, rarely 7; stem with prickles and 



bristles. 

 Leaflets 7; stem with strong prickles but rarely 

 with bristles. 

 Leaflets glandular-pruinose beneath, double- 

 serrated. 

 Leaflets sub-orbicular or oval, usually 



blunt. 

 Leaflets ovate, mostly acute. 

 Leaflets not glandular-pruinose beneath; 

 only rarely double-toothed. 

 Achenes inserted only in the bottom of the bristly 

 hypanthium. 

 Infrastipular prickles decidedly curved. 

 Leaflets finely serrulate. 

 Leaflets coarsely serrate. 

 Leaflets not glaucous. 

 Leaflets glaucous. 

 Infrastipular prickles straight or slightly curved. 

 Leaflets 9-10; stems densely bristly. 

 Leaflets 5-7 ; old stems sparsely bristly. 

 Leaflets shining above. 

 Leaflets not shining above. 



Leaves decidedly pubescent be- 

 neath. 

 Leaves glabrous or pubescent only 

 on the veins beneath. 

 Leaflets not glandular-dentate. 

 Leaflets glandular-dentate. 

 Sepals erect after flowering, long-persistent on the fruit. 

 Flowers bracted. 



Infrastipular prickles present. 



Stems not pubescent; leaves not rugose. 

 Stems pubescent; leaves rugose. 

 Infrastipular prickles not present. 

 Flowers bractless. 



1. R. setigera. 



2. R. rubifolia. 



3. R. gallica. 



4. R. rubiginosa. 



5. R. micrantha. 



6. R. canina. 



7. R. paluslris. 



8. R. gemella. 



9. R. virginiana. 



10. R. nitida. 



9. R. virginiana. 



11. R. Lyoni. 



12. R. Carolina. 



13. R. serrulata. 



14. R. spinosissima. 



15. R. rugosa. 



16. R. Solanderi. 



17. R. pimpinellijolia. 



* Prepared with the assistance of Dr. P. A. Rydberg. Because of scarcity of material 

 and the many doubtful and hybrid specimens it seems wiser to omit phytogeographical 

 and ecological data. 



