1 Lianas.

  2 Lianas climbing by adventitious roots

  2 Lianas climbing by twining or by tendrils.

    3 Lianas climbing by tendrils.

      4 Tendrils branched, leaf-opposed; leaves mostly 5-7-lobed, the margins also serrate or dentate

      4 Tendrils simple (though paired in Smilax in SMILACACEAE), axillary; leaves 3-lobed, the margins entire, serrulate, or prickly.

        5 Leaves longer than wide, entire or prickly-margined; stems usually obviously armed with prickles; flowers 6-merous, greenish, in umbels borne in leaf axils; tendrils stipular, 2 per leaf axil, adnate to the petiole basally

        5 Leaves wider than long, entire or serrulate; stems not armed; flowers 5-merous, blue-purple or yellow, solitary or in small fascicles in leaf axils; tendrils 1 per leaf axil

1 Trees or shrubs. {add: Vernicia in EUPHORBIACEAE, Firmiana in MALVACEAE, Kalopanax in ARALIACEAE, Ficus in MORACEAE}

          6 Trees.

             7 Leaves > 3 dm long and wide; tree monopodial, with a single, unbranched stem (rarely with a few branches).

               8 Leaf lobes > 15, not sublobed; venation of each lobe parallel; fruit a drupe, with 1 seed; [Monocots]

               8 Leaf lobes < 13, most of these sublobed; venation of each lobe pinnate; fruit either a many-seeded berry or a single-seeded nutlet; [Eudicots].

                 9 Petiole attachment marginal; leaf lobes mostly sublobed; fruit a large berry, with many seeds

                 9 Petiole attachment peltate; leaf lobes not sublobed; fruit an nutlet, single-seeded

             7 Leaves < 3 dm long and wide; tree branching; [Eudicots].

                   10 Leaves 2-lobed (deeply notched at the apex, each lobe separated by the midvein, asymmetrical; [peninsular FL and s. TX]

                   10 Leaves 3-5 (-7) lobed; [collectively widespread].

                     11 Leaf blades (3-) 5 (-7) lobed, to 15 cm wide and long, each lobe finely serrate-crenate (>3 teeth per cm of margin) and rarely with a small sub-lobe; multiple fruit spherical and spiky, consisting of multiple bird-beak-like loculicidal capsules; buds axillary

                     11 Leaves 3 (-5)-lobed, to 35 cm wide and long, each lobe coarsely toothed or sublobed, the teeth or sublobes (at most 1-2 per cm of margin) attenuate-acuminate; multiple fruit spherical and merely rough on the surface, consisting of multiple achenes with tawny bristles; buds infrapetiolar (completely hidden in the swollen petiole base)

          6 Shrubs.

                       12 Leaf lobe margins entire (or undulate to sublobed at the tip)

                       12 Leaf lobe margins serrate.

                          13 Leaves glabrous

                          13 Leaves pubescent (slightly or strongly).

                            14 Pubescence of simple hairs; plants armed or not with nodal spines

                              15 Leaves 10-30 cm long and wide; fruit a berry; inflorescence of solitary to a few flowers, or a raceme

                              15 Leaves 2-10 cm long and wide; fruit an aggregate of drupelets; inflorescence a cyme

                            14 Pubescence of stellate hairs; plants unarmed.

                                16 Leaves > 30 cm wide

                                16 Leaves < 15 cm wide

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