Lianas, climbing by tendrils, sprawling, or occasionally shrubby, functionally dioecious (synoecious in V. vinifera). Branches: bark exfoliating (adherent in V. rotundifolia); pith brown, interrupted by nodal diaphragms (continuous through nodes in V. rotundifolia); tendrils 2–3-branched (unbranched in V. rotundifolia), rarely absent, without adhesive discs. Leaves simple. Inflorescences functionally unisexual (bisexual in V. vinifera), leaf-opposed, thyrses. Flowers functionally unisexual (bisexual in V. vinifera); calyx a minute rim, entire or 5-toothed; petals (3–)5(–9), connate distally, forming calyptra; nectary free, (3–)5(–9) glands alternating with stamens; stamens usually (3–)5(–9), sometimes 0 in pistillate flowers; style conic, short. Berries purple or black. Seeds 1–4 per fruit. x = 10.

Distribution

North America, Mexico, West Indies, Central America, n South America, Eurasia, introduced nearly worldwide.

Discussion

Species ca. 70 (19, including 3 hybrids, in the flora).

Vitis is nearly restricted to temperate regions of the northern hemisphere, with one extremely variable species (V. tiliifolia Humboldt & Bonpland ex Schultes) extending into northern South America.

The North American species of Vitis are of considerable economic importance and have played a significant part in commercial viticulture over the last century. The introduction of native North American species into France in the mid 1800s led to the introduction of grape phylloxera, Daktulosphaira vitifoliae, an insect to which the grape of commerce (V. vinifera) is susceptible. Many European vineyards were virtually destroyed by the 1860s. The reconstruction of the European vineyards was made possible by using native North American species, many of which are resistant to grape phylloxera, as rootstocks for and in hybridizations with V. vinifera. Native North American species of Vitis have also played a major role in establishing viticulture as an industry in North America, particularly in areas other than California and Oregon, such as Florida, New York, North Carolina, Ontario, Texas, and Virginia.

Two subgenera of Vitis commonly have been recognized. Subgenus Vitis, which includes the majority of species, is widely distributed in the Northern Hemisphere; subg. Muscadinia, with two species, is restricted to the southeastern United States, the West Indies, and Mexico (G. K. Brizicky 1965; Wen J. 2007). J. K. Small (1903) elevated subg. Muscadinia to generic rank, a treatment followed by some authors, for example A. S. Weakley et al. (2012). However, a recent phylogenetic study of the Vitis-Ampelocissus clade by Liu X. Q. et al. (2015) showed that the Central American Ampelocissus erdvendbergianus Planchon is sister to Vitis and that subg. Muscadinia and subg. Vitis are sister groups. To maintain the monophyly of Vitis and Ampelocissus, A. erdvendbergianus needs to be transferred to Vitis. Recognizing Muscadinia as a distinct genus would require description of a monospecific new genus for A. erdvendbergianus; it makes better sense to maintain a broadly circumscribed Vitis.

In the key and descriptions that follow, nodal diaphragm thickness is in the current year's growth, leaf blade pubescence is on fully mature leaves unless otherwise noted, and berry diameter is of 3–4-seeded berries.

Selected References

None.

Lower Taxa

Vitis subg. Muscadinia, Vitis subg. Vitis

Key

1	Tendrils unbranched; bark adherent; lenticels prominent; pith continuous through nodes [1a. subg. Muscadinia].	Vitis rotundifolia
1	Tendrils branched or absent; bark exfoliating; lenticels inconspicuous or absent; pith interrupted by nodal diaphragms [1b. subg. Vitis].	> 2
2	Flowers bisexual; berries oblong to ellipsoid, skin adhering to pulp.	Vitis vinifera
2	Flowers functionally unisexual; berries globose, skin separating from pulp.	> 3
3	Leaf blade abaxial surface glaucous (sometimes obscured by hairs).	Vitis aestivalis
3	Leaf blade abaxial surface not glaucous (concealed by hairs in V. labrusca).	> 4
4	Tendrils or inflorescences present at 3+ consecutive nodes or almost all nodes.	> 5
5	Leaf blade abaxial surface densely and persistently arachnoid, concealed (except sometimes veins) by hairs; nodal diaphragms 0.5–2.5 mm thick; tendrils at almost all nodes.	Vitis labrusca
5	Leaf blade abaxial surface ± densely arachnoid when young, sparsely arachnoid when mature, visible through hairs; nodal diaphragms 0.3–1.1 mm thick; tendrils usually not at all nodes.	Vitis ×novae-angliae
4	Tendrils or inflorescences present at only 2 consecutive nodes.	> 6
6	Leaf blade abaxial surface densely tomentose, concealed (except sometimes veins) by hairs; berries 12+ mm diam.	> 7
7	Stipules 1.5–4 mm; nodal diaphragms 1.5–3 mm thick; Alabama, Arkansas, Louisiana, Oklahoma, Texas.	Vitis mustangensis
7	Stipules to 1 mm; nodal diaphragms 2.5–6 mm thick; Florida.	Vitis shuttleworthii
6	Leaf blade abaxial surface usually glabrous, moderately arachnoid, or hirtellous, sometimes tomentose (California and s Oregon), visible through hairs; berries 4–12 mm diam. (except 12+ mm in V. ×doaniana and V. ×champinii).	> 8
8	Leaf blades reniform, abaxial surface usually glabrous, sometimes sparsely hirtellous on veins and in vein axils; tendrils absent or only at distalmost nodes.	Vitis rupestris
8	Leaf blades usually cordate to cordate ovate, sometimes orbiculate or nearly reniform, abaxial surface glabrous or hairy; tendrils along length of branchlets.	> 9
9	Nodal diaphragms to 0.5(–1) mm thick; branchlet growing tips enveloped by unfolding leaves.	> 10
10	Plants low to moderately high climbing, much branched; tendrils soon deciduous if not attached to support; branchlets arachnoid or glabrate, growing tips sparsely to densely hairy; inflorescences 3–7(–9) cm.	Vitis acerifolia
10	Plants usually moderate to high climbing, sometimes sprawling, sparsely branched; tendrils persistent; branchlets glabrous or sparsely hirtellous, growing tips glabrous or sparsely hairy; inflorescences (4–)9–12 cm.	Vitis riparia
9	Nodal diaphragms 1–4 mm thick; branchlet growing tips not enveloped by unfolding leaves.	> 11
11	Berries 12+ mm diam.	> 12
12	Leaf blade abaxial surface moderately to densely arachnoid, hirtellous on veins; berries glaucous.	Vitis ×doaniana
12	Leaf blade abaxial surface sparsely arachnoid to glabrate, not hirtellous; berries usually not, sometimes very slightly, glaucous.	Vitis ×champinii
11	Berries 4–12 mm diam.	> 13
13	Leaf blade abaxial surface sparsely to densely tomentose; California, s Oregon.	> 14
14	Berries moderately to heavily glaucous, 8–10 mm diam.; branchlet tomentum thinning in age; nodal diaphragms 3–4 mm thick.	Vitis californica
14	Berries slightly or not glaucous, 4–6 mm diam.; branchlet tomentum usually persistent; nodal diaphragms 1.5–3 mm thick.	Vitis girdiana
13	Leaf blade abaxial surface glabrous or sparsely to densely arachnoid or hirtellous; much of United States, but not California or Oregon.	> 15
15	Plants sprawling to low climbing, shrubby, much branched; tendrils soon deciduous if not attached to means of support; Arizona, Nevada, New Mexico, trans-Pecos Texas, Utah.	Vitis arizonica
15	Plants usually moderate to high climbing, sometimes ± shrubby and sprawling when without support, sparsely branched; tendrils persistent; e United States, including Texas, not in trans-Pecos region.	> 16
16	Branchlets ± angled, densely hirtellous and/or sparsely to densely arachnoid, to glabrate; berries 4–8 mm diam.; nodes sometimes red-banded.	Vitis cinerea
16	Branchlets terete or subterete, glabrous or sparsely arachnoid; berries 8–12 mm diam.; nodes not red-banded.	> 17
17	Nodal diaphragms 2.5–4 mm thick; leaf blades usually deeply lobed, apices long acuminate; branchlets uniformly red, purplish red, or chestnut.	Vitis palmata
17	Nodal diaphragms 1–2.5 mm thick; leaf blades unlobed or shallowly lobed, sometimes deeply lobed on ground shoots, apices acute to short acuminate; branchlets gray to green or brown, if purplish only on one side.	> 18
18	Berries usually with lenticels; inflorescences 3–7 cm; branchlet growing tips sparsely to densely hairy; leaf blades 5–8(–10) cm; branchlets sparsely arachnoid or glabrous.	Vitis monticola
18	Berries without lenticels; inflorescences 9–19 cm; branchlet growing tips glabrous to sparsely hairy; leaf blades (5–)9–18 cm; branchlets glabrous.	Vitis vulpina