66 KOSACEAE 



ROSA. Rose. 



Mostly deciduous and prickly shrubs, sometimes trailing 

 or scrambling to a considerable height, with rather soft wood 

 with small diffused ducts, the first in the spring somewhat lar- 

 ger, and relatively coarse medullary rays; moderately stout 

 usually large and green terete twigs; rounded continuous pith; 

 alternate low openly U-shaped leaf-scars with 3 bundle-traces; 

 no stipule-scars: ovoid sessile buds with several exposed scales; 

 odd-pinnate leaves with dilated stipule-bearing petioles; large 

 perfect usually rosy or white polypetalous perigynous flowers, 

 mostly clustered at ends of the branches; and fleshy ovoid 

 fruiting receptacle (hypanthium) enclosing a number of large 

 hairy akenes. Too large and complex a genus for satisfactory 

 brief analysis: only a very few of the most striking types are 

 noted. 



1. Evergreen. 2. 

 Deciduous. 3. 



2. Glabrate, trailing. (Memorial rose). R. Wichuraiana. 

 Hairy, scrambling, horrid. (Macartney rose) . R. bracteata. 



3. Climbing or forming fountain-like masses. 4. 

 Bushy. 6. 



4. Leaflets about 7: flowers small, in spring. 5. 



Leaflets 5: flowers in summer. (Prairie rose). R. setigera. 



5. Fowers white, early. (Polyantha rose). R. multiflora. 

 Flowers red or pink, in dense clusters, later. 



(Ramblers). R. multiflora platyphylla. 



6. Flowers as in the last, through the season. 



(Baby rambler). R. multiflora platyphylla nana. 



Flowers large or not in dense clusters. 7. 



7. Foliage not strongly scented. 10. 



Foliage heavy-scented, with bristly glands: flowers 



double. 8. 

 Foliage aromatic, not bristly: flowers single. 



(Sweetbriers). R. rubiginosa. 



8. Prickles uniform: teeth of leaflets glandless. 



(Damask rose). R. damascena. 



Prickles very unequal: teeth glandularly toothed. 9. 



