1 Tendrils simple; bark adherent (on all but the largest stems), with prominent lenticels; pith continuous through nodes; leaves relatively small (< 10 cm long and wide) and coarsely toothed, pentagonal in outline but never deeply lobed

1 Tendrils bifid to trifid; bark shedding, the lenticels inconspicuous; pith interrupted by diaphragms at nodes; leaves relatively large (well-developed leaves usually > 10 cm wide and long) and finely toothed, often deeply lobed.

..2 Flowers bisexual; berries ellipsoid, longer than broad; berry with pulp adhering to skin; [alien and cultivated, rarely persistent]

..2 Flowers functionally unisexual; berries globose (isodiametric); berry with skin separating from pulp; [native, collectively widespread].

....3 Mature leaves glaucous beneath (the glaucescence sometimes rather obscured by pubescence); nodes often glaucous; inflorescence rachis (flowering and young-fruiting) orange-red arachnoid-pubescent; [series Aestivales].

......4 Mature 3-4-seeded berries < 9 mm in diameter; mature leaves glabrous to glabrate beneath; nodes usually glaucous; nodal diaphragms usually < 2 mm in diameter

......4 Mature 3-4-seeded berries > 9 mm in diameter; mature leaves slightly to strongly arachnoid-pubescent beneath; nodes usually not glaucous; nodal diaphragms usually > 2 mm in diameter

........5 Twigs and petioles nearly or completely glabrous

........5 Twigs and petioles rusty-tomentose.

..........6 Mature 3-4-seeded berries > 14 mm in diameter; [west of the Mississippi River]

..........6 Mature 3-4-seeded berries 9-14 mm in diameter; [east of the Mississippi River]

....3 Mature leaves not glaucous beneath; nodes not glaucous; inflorescence rachis (flowering and young-fruiting) glabrous, hispid, or white-floccose.

............ 7 Leaves densely pubescent beneath, so as to obscure the surface; [series Labruscae or hybrid involving that series].

............ ..8 Tendrils or inflorescences present at 3 or more consecutive nodes.

............ ....9 Lower leaf surface densely arachnoid-tomentose when young, sparsely so at maturity, the surface visible through the hairs, or the hairs only on the veins; tendrils usually not at all nodes

............ ....9 Lower leaf surface densely and persistently arachnoid-tomentose, the surface (except major veins) hidden by the hairs; tendrils at almost all nodes.

............ ......10 Fruits many, 25-50 in well-developed clusters, the clusters ovoid and well branched, distinctly longer than broad; leaves densely arachnoid-tomentose at maturity

............ ......10 Fruits few, < 20, in a simple globose or spheroidal cluster, about as wide as long; leaves moderately arachnoid-tomentose at maturity

............ ..8 Tendrils or inflorescences present at only 2 consecutive nodes.

............ ........11 Stipules 1.5-4 mm long; nodal diaphragms 1.5-3 mm thick; [AL, MS, LA, TX, and OK]

............ ........11 Stipules < 1 mm long; nodal diaphragms 2.5-6 mm thick; [FL and s. AL]

............ 7 Leaves glabrous or somewhat pubescent beneath (but not so densely as to completely obscure the leaf surface).

............ ..........12 Leaves reniform (wider than long when flattened), folded along the midvein (V-shaped); leaf lower surface glabrous at maturity; tendrils either absent, or when present, only opposite the uppermost nodes (or sometimes extending down the stem); inflorescence rachis (flowering or early-fruiting) glabrous or glabrescent; [series Ripariae]

............ ..........12 Leaves cordate to cordate-ovate (about as wide as long, or longer than wide), not prominently folded along the midvein (near planar); leaf surface glabrous to pubescent at maturity; tendrils present opposite most nodes; inflorescence rachis (flowering or early-fruiting) glabrous, glabrescent, hispid, or white-floccose.

............ ............ 13 Nodal diaphragms > 1 mm wide; growing shoot tips not enveloped by enlarging, unfolded leaves; inflorescence axis (flowering or early-fruiting) hispid and/or white-floccose.

............ ............ ..14 Branchlets of the season more or less terete, glabrous or arachnoid-pubescent; mature 3-4 seeded berries usually > 8 mm in diameter; nodes usually not banded with red pigmentation; inflorescence rachis (flowering or early-fruiting) densely hispid (never floccose); [series Cordifoliae].

............ ............ ....15 Nodal diaphragms > 2.5 mm wide; leaves strongly 3-lobed, the tips usually long-acuminate; branchlets of the season with a red or purplish cast

............ ............ ....15 Nodal diaphragms < 2.5 mm wide; leaves unlobed or shallowly lobed, the tips acute to short-acuminate; branchlets of the season gray, green, or brown (sometimes purple only on one side)

............ ............ ..14 Branchlets of the season angled, arachnoid-pubescent and/or hirtellous-pubescent (or nearly glabrous); mature 3-4 seeded berries < 8 mm in diameter; nodes frequently banded with red pigmentation; inflorescence rachis (flowering or early-fruiting) white-floccose (and sometimes also hispid); [series Cinerescentes].

............ ............ ......16 Branchlets of the season sparsely to densely hirtellous pubescent, often with arachnoid pubescence as well; leaf undersurfaces usually more-or-less uniformly hirtellous on the veins; [western, east to w. KY, w. TN, sc. AL, and Panhandle FL]

............ ............ ......16 Branchlets of the season lacking evident hirtellous trichomes (if present, obscured by the arachnoid pubescence; leaf undersurfaces lacking hirtellous pubescence, or only very sparsely so; [collectively widespread in our area].

............ ............ ........17 Branchlets glabrate to only slightly arachnoid-pubescent; nodes usually banded with red pigmentation; leaves glabrous to very slightly arachnoid-pubescent beneath; [mostly of the Piedmont and Mountains]

............ ............ ........17 Branchlets slightly to densely arachnoid-pubescent; nodes usually not banded with red pigmentation; leaves slightly to densely arachnoid-pubescent beneath; [mostly of the Coastal Plain]