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-p.u.b.escent beneath =Sweetbrier, Rosa rubiginosa.=
15b. Leaves glabrous or minutely p.u.b.escent =Swamp Rose, Rosa carolina.=
16a. Stems trailing or creeping --17.
16b. Stems erect, ascending, or arched --19.
17a. Stems distinctly shrubby and th.o.r.n.y (Dewberry) --18.
17b. Stems almost herbaceous, without thorns =Dwarf Raspberry, Rubus triflorus.=
18a. Leaves thin, dull above; fruit black, large and juicy =Dewberry, Rubus villosus.=
18b. Leaves firm or thick, shining above; fruit reddish, small, consisting of a few sour drupelets =Swamp Dewberry, Rubus hispidus.=
19a. Ripe fruit dropping away from the white receptacle or core; terminal leaflet of each leaf with a long stalk, while the lateral leaflets are sessile or nearly so (Raspberry) --20.
19b. Ripe fruit and receptacle or core dropping together; all the leaflets on stalks which are approximately equal in length (Blackberry) --22.
20a. Stem very glaucous with a whitish or bluish waxy deposit; fruit black =Black Raspberry, Rubus occidentalis.=
20b. Stem not glaucous; fruit red --21.
21a. Calyx velvety-p.u.b.escent =Red Raspberry, Rubus idaeus.=
21b. Calyx bristly-hispid =Red Raspberry, Rubus idaeus var. aculeatissimus.=
22a. Pedicels with gland-tipped hairs, but no p.r.i.c.kles =Blackberry, Rubus allegheniensis.=
22b. Pedicels with p.r.i.c.kles =Blackberry, Rubus nigricans.=
22c. Pedicels with neither p.r.i.c.kles nor gland-tipped hairs --23.
23a. Leaves downy beneath =Blackberry, Rubus frondosus.=
23b. Leaves smooth beneath =Blackberry, Rubus canadensis.=
24a. Ovaries 1 or more, superior (attached to the surface of the receptacle, but not concealed within it or united to it) --25.
24b. Ovary 1, inferior (permanently enclosed within the receptacle, with only the styles protruding) --38.
25a. Ovaries more than 1 --26.
25b. Ovary 1 --30.
26a. Leaves serrate --27.
26b. Leaves lobed --28.
27a. Leaves glabrous or very nearly so (8-20 dm. high; flowers white or pinkish, summer) =Meadow-sweet, Spiraea salicifolia.=
27b. Leaves closely p.u.b.escent beneath (5-15 dm. high; flowers pink, summer) =Hardhack, Spiraea tomentosa.=
28a. Flowers showy, purple or white, 3-4 cm. broad --29.
28b. Flowers white, about 1 cm. wide (1-3 m. high; flowers in early summer) =Ninebark, Physocarpus opulifolius.=
29a. Flowers purple =Flowering Raspberry, Rubus odoratus.=
29b. Flowers white =Salmonberry, Rubus parviflorus.=
30a. Flowers in racemes (trees or tall shrubs; flowers white, in late spring) --31.
30b. Flowers in small umbels or corymbs (flowers white, in spring) --32.
31a. Leaves oblong, the points of their teeth incurved =Black Cherry, Prunus serotina.=
31b. Leaves obovate, the points of their teeth spreading =Choke Cherry, Prunus virginiana.=
32a. Flowers about 1 cm. wide --33.
32b. Flowers about 1.5-2.5 cm. wide --36.
33a. Low shrubs, with the spatulate or oblong leaves widest above the middle --34.
33b. Erect tall shrubs or small trees, with the leaves widest below the middle --35.
34a. An erect shrub (5-10 dm. high) =Appalachian Cherry, Prunus cuneata.=
34b. A prostrate or ascending shrub (3-15 dm. high) =Sand Cherry, Prunus pumila.=
35a. Leaves very broadly ovate, almost as wide as long (small tree) =Perfumed Cherry, Prunus mahaleb.=
35b. Leaves oblong-lanceolate, about 3 times as long as broad (shrub or small tree, 2-10 m. high) =Pin Cherry, Prunus pennsylvanica.=
36a. Sepals glandular-serrate (tall shrub or small tree) =Wild Plum, Prunus nigra.=
36b. Sepals entire --37.
37a. Leaves with sharp teeth, frequently bristle-tipped; a native species (tall shrub or small tree, frequently growing in thickets) =Wild Plum, Prunus americana.=
37b. Leaves with obtuse teeth; a species escaped from cultivation (widely branched tree) =Cherry, Prunus cerasus.=
38a. Trees, in cultivation or escaped from cultivation near roads or dwellings, with showy flowers 2.5-5 cm. across, edible fruits, and no thorns (spring) --39.