.52 



5a. Leaves pubescent on the lower surface 



Rowan Tree, Pyrus ancnparia. 



5b. Leaves glabrous beneath when mature (small trees; flowers white, 

 in early summer or late spring) (Mountain Ash) 6. 



6a. Leaves acuminate at the apex 



Mountain Ash, Pyrus americana. 

 6b. Leaves obtuse or acute at the apex 



Mountain Ash, Pyrus sitchensis. 



7a. Flowers yellow (5 10 dm. high; summer) 



Cinquefoil, Potentilla fruticosa. 



7b. Flowers pink or red, rarely white, 4 10 cm. across (shrubs, 

 5 15 dm. high, or climbing; stems usually thorny; flowers 

 in early summer) (Rose) 8. 



7c. Flowers white, 1 3 cm. across (4 20 dm. high; flowers in late 

 spring) 16. 



8a. Leaflets on most of the leaves 3; styles cohering in a column 

 which protrudes from among the stamens 



Climbing: Rose, Rosa setigera. 

 8b. Leaflets 5 11; styles not cohering in a protruding column 9. 



9a. Sepals persistent on the fruit after flowering 10. 



9b. Sepals soon deciduous from the young fruit after flowering 14. 



lOa. A pair of spines below each leaf larger than the other 



spines 11. 

 lOb. Spines all alike in size or nearly so, or absent completely 



12. 



lla. Sepals entire Wild Rose, Rosa woodsiL 



lib. Sepals pinnatifid Dog Rose, Rosa canina.' 



12a. Stems with few thorns or none at all 



Wild Rose, Rosa blanda, 



12b. Stems prickly 13. 



13a. Fruit somewhat pear-shape, narrowed toward the base. 



Wild Rose, Rosa acicularis, 

 13b. Fruit globose, rounded at the base 



Wild Rose, Rosa acicularis var. bourgeauiana. 



14a. The pair of spines at the base of each leaf straight or 

 nearly so Wild Rose, Rosa humilis. 



14b. The pair of spines at the base of each leaf distinctly re- 

 curved or hooked 15. 



15a. Leaves densely glandular-pubescent beneath 



Sweetbrier, Rosa rubiginosa. 

 15b. Leaves glabrous or minutely pubescent 



Swamp Rose, Rosa Carolina, 



16a. Stems trailing or creeping 17. 



16b. Stems erect, ascending, or arched 19-. 



