Vitis arizonica
Vitis aestivalis
canyon grape
summer grape, summer or post oak or big summer or silverleaf or blue grape, vigne d'été
bark exfoliating in plates;
nodal diaphragms 1.5–3 mm thick;
branchlets slightly angled when young, becoming terete, arachnoid or arachnoid-floccose, sometimes glabrescent, growing tips not enveloped by unfolding leaves;
tendrils along length of branchlets, soon deciduous if not attached to support, branched, tendrils (or inflorescences) at only 2 consecutive nodes;
nodes not red-banded.
bark exfoliating in shreds;
nodal diaphragms 1–4 mm thick;
branchlets terete, tomentose, arachnoid-floccose, or glabrous, growing tips not enveloped by unfolding leaves;
tendrils along length of branchlets, persistent, tendrils (or inflorescences) at only 2 consecutive nodes;
nodes not red-banded.
stipules 1.5–3 mm;
petiole 1/2 to ± equaling blade;
blade cordate to cordate-ovate, 5–12 cm, usually unlobed to 3-shouldered, sometimes shallowly 3-lobed, apex acute to acuminate, abaxial surface not glaucous, moderately to sparsely arachnoid, visible through hairs, veins and vein axils sometimes only hirtellous, adaxial surface sparsely arachnoid or glabrous.
stipules 1–4 mm;
petiole ± equaling blade;
blade cordate to orbiculate, 7–25 cm, unlobed to 3-shouldered or 3–5-lobed, sometimes deeply so, apex acute to short acuminate, abaxial surface glaucous, ± arachnoid or floccose, visible through hairs, hairs usually rusty, sometimes whitish, veins and vein axils sometimes hirtellous, adaxial surface glabrous or puberulent.
4–12 cm.
7–20 cm.
functionally unisexual.
functionally unisexual.
black, slightly or not glaucous, globose, 6–10 mm diam., skin separating from pulp;
lenticels absent.
black, glaucous, globose, 8–20 mm diam., skin separating from pulp;
lenticels absent.
= 38.
= 38.
Vitis arizonica
Vitis aestivalis
Vitis arizonica is variable and intergrades with V. girdiana in southern Nevada; it is in need of in-depth field and experimental studies. Some authors have recognized two varieties of this species (vars. arizonica and glabra), but the characters used to distinguish them intergrade so freely that their recognition does not seem justified.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Vitis aestivalis is sometimes confused with V. cinerea. However, the glaucous abaxial leaf surfaces, more heavily glaucous and larger berries, terete branchlets that are less evenly pubescent, preference for better drained, drier habitats, and earlier blooming period distinguish V. aestivalis from V. cinerea.
Several varieties have been recognized based on leaf and young stem pubescence and fruit sizes (B. L. Comeaux et al. 1987; M. O. Moore 1991). The boundaries of the varieties are highly inconsistent and it is often difficult to apply the varietal concepts in the field. Recent molecular evidence supports the monophyly of V. aestivalis, but none of the varieties were supported as monophyletic (Wan Y. et al. 2013).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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