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Vitis

The leaf blades of Vitis have two very different types of hairs, and distinguishing these pubescence types is important for species recognition. One type of hair lies parallel with the surface of the leaf blade. It is a fine, tangled hair and can be categorized as tomentose. The other type of hair is ± spreading (i.e., it does not lie parallel with the leaf blade surface). This hair is relatively thick and straight compared with the tomentum. Reference: Moore (1991).

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V. labrusca
1a. Tendrils and/or panicles produced from 3–7 successive nodes; berries 10–20 (–25) mm thick; abaxial surface of leaf blades persistently pubescent with red-brown (later turning gray), tomentose hairs, the surface of the leaf blade largely or completely hidden by the hairs; axis of the inflorescence tomentose
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1b. Tendrils and/or panicles produced from no more than 2 successive nodes; berries 5–12 mm thick (to 22 mm thick in V. vinifera); abaxial surface of leaf blades glabrate to sparsely pubescent at maturity, much of the surface of the leaf blade clearly visible (one variety of V. aestivalis more heavily pubescent); axis of the inflorescence glabrous to sparsely pubescent
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  V. aestivalis
  2a. Abaxial surface of leaf blade not green, either glaucous or somewhat concealed by a thin layer of red-brown tomentum; nodes of branchlets often glaucous
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  2b. Abaxial surface of leaf blades green, the pubescence, if present, primarily restricted to the veins or occurring in patches; nodes of branchlets not glaucous
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    V. vinifera
    3a. Leaf blades orbicular to suborbicular, often prominently lobed with deep sinuses, commonly with some patches of thin tomentum on the abaxial surface (especially in early season); exocarp of fresh fruit separated from mesocarp only with difficulty
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    3b. Leaf blades ovate to orbicular, unlobed or with obscure to evident lobes, lacking tomentose hairs (though usually with straight hairs); exocarp of fresh fruit readily separated from mesocarp
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      V. riparia
      4a. Nodal diaphragms 0.5–1 (–2) mm thick; leaf blades with large teeth that taper to thin tips, the teeth mostly 5–20 mm long and with one or both tooth margins concave [Fig. 944]; growing branchlet tips enveloped by enlarged, unfolding leaves; berry prominently glaucous
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      4b. Nodal diaphragms 2–5 mm thick; leaf blades with shorter teeth that do not taper to thin tips, the teeth usually less than 5 mm long and with straight or convex margins [Fig. 942]; growing branchlet tips not enveloped by unfolding leaves; berry not or only thinly glaucous
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        V. vulpina
        5a. Branchlets usually green, maturing gray to brown (if with any purple or red coloration, this restricted to one side of the branchlet); leaf blades acute to short-acuminate at the apex; seeds 3–5 mm long
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        V. palmata
        5b. Branchlets red to purple throughout, maturing red-brown to dark red-brown; leaf blades acuminate to long-acuminate at the apex; seeds 4–7 mm long

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Show photos of: Each photo represents one species in this genus.