1 Leaves serrate.

  2 Leaf venation palmate, the leaf often lobed or at least pentagonal in shape (as well as serrate); plants climbing by leaf-opposed tendrils

  2 Leaf venation pinnate, the leaf neither lobed nor pentagonal; plants climbing by other mechanisms (see below).

    3 Plants climbing by axillary tendrils; [FL]

    3 Plants climbing by adventitious roots, by twining, or by growing through bark layers of Taxodium ascendens or Chamaecyparis thyoides; [collectively widespread in our region].

      4 Plants climbing by adventitious roots; leaf base cordate or subcordate, and also slightly to strongly oblique

      4 Plants climbing by twining, or by growing through bark layers of Taxodium ascendens or Chamaecyparis thyoides; leaf base cuneate, rounded, or cordate.

        5 Leaves strongly cordate at the base, 7-15 cm wide

        5 Leaves cuneate, rounded, or subcordate at the base, 0.3-8 cm wide.

          6 Leaf blades mostly 2-6 cm long, 0.3-2 cm wide; plants climbing by growing through bark layers of Taxodium ascendens or Chamaecyparis thyoides

          6 Leaf blades mostly 6-13 cm long, 3-8 cm wide; plants climbing by twining

1 Leaves entire.

             7 Stems with well-developed prickles; tendrils paired, stipular (diverging from the leaf petiole above its base); [Monocots]

             7 Stems lacking prickles; tendrils either absent or (if present) not stipular and paired; [Eudicots or Basal Angiosperms].

               8 Plant climbing by dense, reddish adventitious roots

               8 Plant climbing by twining or by tendrils.

                 9 Plant climbing by tendrils

                 9 Plant climbing by twining.

                   10 Leaves elliptic or ovate, obviously longer than broad, most leaves > 1.4× as long as wide; leaf blade base narrowly cuneate, broadly cuneate, rounded, or subcordate.

                     11 Leaves 3-8 cm long, rounded to broadly cuneate at the base and rounded or obtuse at the apex; lateral leaf veins straight, parallel, not forking; inflorescence a terminal thyrse or panicle

                     11 Leaves 6-15 cm long, cuneate at the base and acuminate at the apex; lateral leaf veins forking at or beyond the middle; inflorescence a solitary, axillary flower

                   10 Leaves orbicular to very widely ovate, most leaves < 1.4× as long as wide; leaf blade base deeply cordate, subcordate, rounded, or broadly cuneate

                       12 Leaf venation pinnate, but “pseudopalmate”, with 3 primary veins from the marginal point of attachment of the petiole, the 2 lateral veins then promptly rebranching (< 1 cm from the leaf base) into 2-3 prominent veins (the remainder of the venation pinnate along the midvein); basalmost pair of primary veins exposed (lacking leaf tissue) on their basal side for > 2 mm; leaf blade base deeply cordate; leaf with no tendency to lobing, the leaf outline convex from the base to the apex (except in the immediate vicinity of the petiole and sometimes immediately near a slightly acuminate apex

                       12 Leaf venation palmate, with (3-) 5-9 primary veins from the marginal or peltate point of attachment of the petiole, these primary veins then rebranching well above the leaf base; basalmost pair of primary veins completely included within leaf tissue; leaf blade base cordate, subcordate, rounded, or broadly cuneate; leaf with a tendency to lobing, the leaf outline with 1 or more concave areas between the base and the apex (except Cissampelos of s. FL)