8. Vitis rupestris Scheele, Linnaea. 21: 591. 1848.
Rock or sand grape Rock or sand grape
Vitis rupestris var. dissecta Eggert ex L. H. Bailey
Plants sprawling to low climbing, shrubby, much branched. Branches: bark tardily exfoliating in plates; nodal diaphragms to 1 mm thick; branchlets terete, usually glabrous, sometimes sparsely hirtellous, growing tips enveloped by unfolding leaves; tendrils absent or only at distalmost nodes, soon deciduous if not attached to support, branched, tendrils (or inflorescences) at only 2 consecutive nodes; nodes not red-banded. Leaves: stipules 3–6.5 mm; petiole 1/2 blade; blade reniform, conduplicately folded, 5–10 cm, apex acute to short acuminate, usually 3-shouldered, rarely shallowly 3-lobed, abaxial surface not glaucous, usually glabrous, visible through hairs, veins and vein axils sometimes sparsely hirtellous, adaxial surface usually glabrous. Inflorescences 4–7 cm. Flowers functionally unisexual. Berries black, slightly glaucous, globose, 8–12 mm diam., skin separating from pulp; lenticels absent. 2n = 38.
Flowering Apr–May; fruiting Aug–Sep. Gravelly banks, river bottoms, stream beds, washes, often calcareous soils; 70–500 m; Ark., D.C., Ind., Ky., Md., Mo., Okla., Pa., Tenn., Tex., Va., W.Va.
Vitis rupestris once was widely scattered throughout most of its range, but now mostly is rare and may have been extirpated in many locations, apparently due to habitat loss. It is most common in the Ozark region of northern Arkansas and the southern half of Missouri, but is imperiled elsewhere (http://explorer.natureserve.org). It is persisting from cultivation in California and some other locations (J. Wen, pers. obs.; E. B. Wada and M. A. Walker, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=48433). Reports from Illinois were based on misidentifications (R. H. Mohlenbrock 2014). The species was used to develop many grape hybrids due to its resistance to disease (J. Gerrath et al. 2015)