| | 1. Flower bisexual; fruit ± ovoid, skin adherent to pulp; stem hairy when young, generally becoming glabrous |
| V. vinifera |
| | 1' Flower unisexual; fruit spheric, skin separating from pulp; stem ± tomentose when young, sometimes becoming sparsely so |
| |
| | 2. Fruit purple, very glaucous, when 3–4-seeded generally > 8 mm wide; seed structure opposite attachment scar generally raised; stipules generally < 3.5 mm; stem tomentose when young, becoming less so |
| V. californica |
| | 2' Fruit black, slightly to not glaucous, when 3–4-seeded generally < 8 mm wide; seed structure opposite attachment scar generally sunken; stipules generally > 3.5 mm; stem densely tomentose when young, ± remaining so |
| V. girdiana
|