1 Leaves 3-foliolate; shrub to 4 m tall; inflorescence of small lateral and terminal clusters; pedicels < 1 mm long, with bracteoles; [subgenus Lobadium; section Lobadium].

  2 Leaflets usually glabrous below; leaflet margins not ciliate; terminal leaflets 15-33 mm long; [western edge of our area, in sw. AR, e. OK and e. TX westwards]

  2 Leaflets usually pubescent beneath; leaflet margins ciliate; terminal leaflets 15-60 mm long; [collectively widespread in our area].

    3 Terminal leaflets 15-40 mm long; plants spreading to prostrate; flowers produced at or after the expansion of the leaves; [sandy areas in OH, IN, IL, and IA]

    3 Terminal leaflets 25-60 mm long; plants erect; flowers produced before, at, or after expansion of the leaves; [collectively widespread in our area].

      4 Terminal leaflets broadly rhombic or obovate, 3-lobed, and also scalloped or toothed, rounded or angled at the tip; flowers produced at or after the expansion of the leaves; pedicels 2-3 mm long, glabrous to densely woolly; petals usually hairy on the inner surface; fruits 5-6 mm in diameter; [west of the Mississippi River and disjunct eastwards in KY, TN, and AL]

1 Leaves (3-) 5-31-foliolate; shrub or small tree, to 12 m tall; inflorescence either of dense, terminal panicles or small lateral and terminal clusters; pedicels 1.5-2.5 mm long, lacking bracteoles.

        5 Leaves (3-) 5-9-foliolate; leaflets < 2 cm long, < 6 mm wide; [western edge of our area]; [subgenus Lobadium; section Rhoeidium]

        5 Leaves 5-31-foliolate; leaflets > 2 cm long, > 6 mm wide; [collectively widespread].

          6 Leaves 5-9-foliolate; leaflets < 4 cm long, 1-1.5× as long as wide, evergreen, softly puberulent below; [subgenus Lobadium; section Styphonia]

          6 Leaves 5-31-foliolate; leaflets 2-9 cm long, 2-9× as long as wide, deciduous (turning orange to scarlet in the fall), glabrous, glabrescent, or pubescent (with long hairs) beneath; [subgenus Rhus].

             7 Rachis of the leaf winged between each pair of adjacent leaflets; stems and petioles puberulent; leaflets entire to remotely toothed.

               8 Leaflets 4-9× as long as wide; rachis + wings < 3.5 mm wide (at widest points); [western edge of our area, in e. OK and e. TX, westward]

               8 Leaflets 2-4× as long as wide; rachis + wings > 4 mm wide (at widest points); [collectively widespread in our area].

                 9 Leaflets 11-25, attenuate to base, 2-9 cm long, 1-2 cm wide, either >3× as long as wide or < 4 cm long; leaflet margins entire (rarely serrate); leaflet apex rounded, obtuse, acute, or acuminate (often at least the more basal leaflets with an obtuse tip)

                 9 Leaflets 5-13, rounded to base on the upper side, 4-9 cm long, 1.5-5 cm wide, > 2.5× as long as wide; leaflet margins entire or serrate; leaflet apex acute or acuminate tip

             7 Rachis of the leaf not winged between each pair of adjacent leaflets (sometimes winged between the last 1 or 2 pairs of leaflets on each side of the rachis); stems and petioles either densely villous or essentially glabrous; leaflets sharply and rather coarsely serrate.

                   10 Leaflets densely pubescent (rarely sparsely pubescent); short shrubs to 1 m tall; stems densely long-pubescent; rachis of the leaf often winged terminally; leaflets mostly ovate, averaging about 2× as long as wide, acute

                   10 Leaflets glabrous, glaucous beneath; medium shrubs to small trees, to 12 m tall; stems densely long-pubescent or essentially glabrous; rachis of the leaf not winged; leaflets mostly lanceolate, averaging 3-4× as long as wide, acuminate.

                     11 Stems essentially glabrous; pubescence of the fruit short and blunt-tipped

                     11 Stems densely long-pubescent; pubescence of the fruit long and pointed