1 Leaves (3-) 5-7-foliolate, at least some leaves (on a plant with more than 5 nodes) 5-7-foliolate; trailing juvenile plants with 5-7-foliolate leaves towards the base and 3-foliolate (or rarely one or a few 1-foliolate leaves) towards the tip; [native].

  2 Larger leaves 7-foliolate; leaflets thick and fleshy in texture when fresh, 3-5 cm long; leaflets > 1.8× as long as wide; [of c. TX, barely entering our region on the western edge of e. TX]

  2 Larger leaves 5-foliolate; leaflets herbaceous in texture when fresh, 4-12 cm long; leaflets < 1.5× as long as wide; [collectively widespread in our area].

    3 Inflorescence with a well-developed (zigzag) central axis, the dichotomous branches very unequal, the inflorescence therefore paniculiform, with a total of 25-200+ flowers; tendrils with mostly 3-8 branches, most or all branches terminating with adhesive disks (though young shoots may not have the disks yet formed); leaves usually dull above, medium green; leaflets sessile, subsessile, or short-petiolulate (usually < 5 mm long); leaflet margins toothed primarily past the widest point, with few and obscure teeth below that point; berries 4-8 mm in diameter; [widespread in our area]

    3 Inflorescence without a well-developed central axis, the dichotomous branches relatively equal, the inflorescence therefore corymbiform, as wide or wider than long, with 2-3 main branches, with a total of 10-60 flowers; tendrils with mostly 3-5 branches, usually none terminating in adhesive disks (though sometimes swollen at the tip); leaves usually glossy above, often dark green; leaflets borne on long petiolules, often > 10 mm long; leaflet margins coarsely and jaggedly toothed, the teeth usually prominent in the lower half of each leaflet as well as the upper half; berries 6-12 mm in diameter; [from e. VA, n. WV northward, but also cultivated and spreading from horticultural use]

1 Leaves simple, sometimes shallowly or deeply 3-5 (-7)-lobed.

  2 Tendrils twining, lacking adhesive disks.

    3 Petals connate at their tips, falling together; pith tan to brown, interrupted by a diaphragm at each node (subg. Vitis) or continuous through the node (subg. Muscadinia); bark adherent (subg. Muscadinia) or exfoliating (subg. Vitis); tendrils bifid or trifid (subg. Vitis) or simple (subg. Muscadinia); [tribe Viteae].

    3 Petals separate at their tips, falling individually; pith white, continuous through the node; bark adherent; tendrils bifid or trifid

      4 Petals 5; stamens 5; upper leaf surfaces glabrous; [tribe Ampelopsideae]

      4 Petals 4; stamens 4; upper leaf surfaces puberulent with upright, whitish-gray hairs; [tribe Cisseae]

1 Leaves compound with either 3-5 (-7) or numerous leaflets.

        5 Leaves bipinnate to tripinnate, the leaflets on at least the better-developed leaves > 7; inflorescences axillary; [tribe Ampelopsideae]

        5 Leaves 3-7-foliolate; inflorescences axillary, leaf-opposed, or terminal.

          6 Leaflets sessile; leaflets pinnately lobed; [tribe Ampelopsideae]

          6 Leaflets petiolulate; leaflets toothed or entire.

             7 Leaves pedately 5-foliolate (the lateral 2 leaflets on either side borne on a common stalk, attached to one another above the summit of the petiole); [tribe Cayratieae]

             7 Leaves palmately 3-7-foliolate (the petiolules of all leaflets joined at the summit of the petiole).

               8 Inflorescences leaf-opposed or apparently terminal; leaves 3-7-foliolate; [tribe Parthenocisseae].

               8 Inflorescences axillary or leaf-opposed; leaves 3-foliolate (even the largest and best-developed).

                 9 Leaves fleshy, the blades > 1 mm thick when fresh; inflorescence axillary; [tribe Cayratieae]

                 9 Leaves herbaceous, the blades thin; inflorescence leaf-opposed; [tribe Cisseae]