=Rowan Tree, Pyrus aucuparia.=

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.

10a. A pair of spines below each leaf larger than the other spines
--11.

10b. Spines all alike in size or nearly so, or absent completely
--12.

11a. Sepals entire =Wild Rose, Rosa woodsii.=

11b. 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
recurved 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.

17a. Stems distinctly shrubby and thorny (Dewberry) --18.

17b. Stems almost her