1b. Leaves simple --3.
2a. Pith of the twigs white; inflorescence flattened or convex =Elder, Sambucus canadensis.=
2b. Pith of the twigs brown; inflorescence pyramidal =Elder, Sambucus racemosa.=
3a. Plant trailing; flowers nodding, in pairs (1 dm. high; flowers pink, summer) =Twin Flower, Linnaea borealis var. americana.=
3b. Erect herbs (6-12 dm. high; flowers dull-red, axillary, early summer) (Feverwort) --4.
3c. Shrubs, small trees, or woody vines --5.
4a. Leaf-bases broadly connate and 2-5 cm. wide =Feverwort, Triosteum perfoliatum.=
4b. Leaf-bases narrowly connate, not over 1 cm. wide =Feverwort, Triosteum aurantiac.u.m.=
5a. Climbing vines (spring and early summer) (Honeysuckle) --6.
5b. Erect or spreading shrubs or small trees --11.
6a. Flowers in 2-flowered axillary cl.u.s.ters (flowers white or pink) =Honeysuckle, Lonicera j.a.ponica.=
6b. Flowers in terminal cl.u.s.ters --7.
7a. Leaves distinctly p.u.b.escent beneath (flowers yellow) --8.
7b. Leaves glabrous beneath, or very minutely p.u.b.erulent --9.
8a. Leaves p.u.b.escent above =Honeysuckle, Lonicera hirsuta.=
8b. Leaves glabrous above =Honeysuckle, Lonicera glaucescens.=
9a. Corolla purple on the outside, glabrous within =Honeysuckle, Lonicera caprifolium.=
9b. Corolla yellow on the outside (or slightly tinged with purple), p.u.b.escent within --10.
10a. Corolla-tube 6-8 mm. long =Honeysuckle, Lonicera dioica.=
10b. Corolla-tube 11-14 mm. long =Honeysuckle, Lonicera sullivantii.=
11a. Corolla tubular at base; style long and slender --12.
11b. Corolla rotate or somewhat bell-shape, style very short (flowers white, late spring or early summer) --22.
12a. Flowers yellow or yellowish (spring and early summer) --13.
12b. Flowers white, pink, or red --18.
13a. Leaves serrate (5-10 dm. tall) =Bush Honeysuckle, Diervilla lonicera.=
13b. Leaves entire; flowers in pairs (Honeysuckle) --14.
14a. Each pair of flowers subtended by 2 broad leaf-like bracts (1-3 m. high) =Honeysuckle, Lonicera involucrata.=
14b. Bracts at the base of each pair of flowers linear or narrowly lanceolate --15.
15a. Native species of woods and bogs --16.
15b. Introduced species, growing mostly near dwellings; leaves very p.u.b.escent beneath =Honeysuckle, Lonicera xylosteum.=
16a. Peduncles 15 mm. long or more (1-4 m. high) --17.
16b. Peduncles about 5 mm. long (1 m. high, or less) =Honeysuckle, Lonicera coerulea var. villosa.=
17a. Leaves ciliate =Honeysuckle, Lonicera canadensis.=
17b. Leaves not ciliate =Honeysuckle, Lonicera oblongifolia.=
18a. Corolla irregular, over 1 cm. long (1-4 m. high; spring) =Honeysuckle, Lonicera tatarica.=
18b. Corolla regular, less than 1 cm. long (5-15 dm. high; flowers white or pink, in axillary cl.u.s.ters, early summer) --19.
19a. Flowers in axillary spikes =Wolfberry, Symphoricarpos occidentalis.=
19b. Flowers almost sessile in the axils --20.
20a. Flowers numerous in each axil =Indian Currant, Symphoricarpos...o...b..culatus.=
20b. Flowers 1 or 2 in each axil (s...o...b..rry) --21.
21a. Leaves green beneath =s...o...b..rry, Symphoricarpos racemosus.=
21b. Leaves whitened beneath =s...o...b..rry, Symphoricarpos racemosus var. pauciflorus.=
22a. Leaves palmately lobed --23.
22b. Leaves not lobed --25.
23a. Outermost flowers of the cl.u.s.ter enlarged and imperfect (1-4 m.
high) =Cranberry Tree, Viburnum opulus var. americanum.=
23b. All flowers of the cl.u.s.ter alike --24.
24a. Flower-cl.u.s.ters 4-10 cm. broad (1-2 m. high) =Arrow Wood, Viburnum acerifolium.=
24b. Flower-cl.u.s.ters 2-3 cm. broad =Squashberry, Viburnum pauciflorum.=
25a. Outer flowers of the cl.u.s.ter enlarged and imperfect (1-3 m. high) =Hobble-bush, Viburnum alnifolium.=