Shrubs, with simple leaves and small flowers in axillary or terminal clusters in early summer; sepals, petals, and stamens each 4 to 5, or petals none.
| 1a. Leaves with a single mid-vein; flowers in axillary clusters,
greenish (Buckthorn) [— 2.] | |
| 1b. Leaves with 3-5 principal veins; flowers in dense terminal clusters,
white (Red-root) [— 3.] | |
| 2a. Lateral veins 3-4 pairs (stout shrub, frequently thorny,
escaped from cultivation) | Buckthorn, Rhamnus cathartica. |
| 2b. Lateral veins 6-9 pairs (1 m. high or less; in swamps and bogs) | Buckthorn, Rhamnus alnifolia. |
| 3a. Leaves ovate, rounded or cordate at the base, 2-5 cm. wide or more
(4-8 dm. high) | Red-root, Ceanothus americanus. |
| 3b. Leaves elliptical-lanceolate, 2 cm. wide or less (3-8 dm. high) | Red-root, Ceanothus ovatus. |
Shrubs, climbing by tendrils or hold-fast roots, with palmately lobed or palmately compound leaves and small greenish flowers in panicles or flattened clusters; petals and sepals each 4 or 5; fruit a berry.
| 1a. Leaves compound (summer) (Virginia Creeper) [— 2.] | |
| 1b. Leaves simple (late spring) (Grape) [— 4.] | |
| 2a. Branches of the tendrils chiefly ending in adhesive disks [— 3.] | |
| 2b. Branches of the tendrils twining, or rarely with a few disks | Virginia Creeper, Psedera vitacea. |
| 3a. Stem and foliage glabrous | Virginia Creeper, Psedera quinquefolia. |
| 3b. Stem and foliage pubescent, at least when young | Virginia Creeper, Psedera quinquefolia var. hirsuta. |
| 4a. Leaves conspicuously pubescent beneath [— 5.] | |
| 4b. Leaves glabrous beneath when mature, or pubescent on the veins
only [— 6.] | |
| 5a. A tendril or flower-cluster opposite each leaf | Fox Grape, Vitis labrusca. |
| 5b. No tendril opposite each third leaf | Summer Grape, Vitis aestivalis. |
| 6a. Pith continuous through the joints of the stem | Fox Grape, Vitis rotundifolia. |
| 6b. Pith interrupted by the solid joints [— 7.] | |
| 7a. Leaf-lobes with rounded angles between them | Summer Grape, Vitis bicolor. |
| 7b. Leaf-lobes with sharp angles between them [— 8.] | |
| 8a. Leaves coarsely toothed, unlobed or slightly 3-lobed | Frost Grape, Vitis cordifolia. |
| 8b. Leaves sharply toothed, prominently lobed | Frost Grape, Vitis vulpina. |
Trees, with alternate, simple, palmately veined leaves, and clusters of fragrant white flowers in late spring arising from the middle of a leaf-like bract; sepals and petals each 5; stamens numerous, but united into 5 sets.