This species is an inhabitant of southwestern Texas, extending eastward and northward into New Mexico, southern Missouri, Indiana and Tennessee to southern Pennsylvania and the District of Columbia. Its favorite places are gravelly banks and bars of mountain streams or the rocky beds of dry watercourses. This species is rather variable both in type and growth. It was introduced into France at about the same time as Vulpina, and the French vineyardists selected the most vigorous and healthy forms for grafting stock. These pass under the various names of Rupestris Mission, Rupestris du Lot, Rupestris Ganzin, Rupestris Martin, Rupestris St. George and others. In France, these varieties have given particularly good results on bare, rocky soils with hot, dry exposures. In California, Rupestris does not flourish in dry locations, and as it suckers profusely and does not take the graft as readily as Vulpina and Æstivalis, it is not largely propagated.
The clusters of fruit are small, with berries about the size of a currant and varying from sweet to sour. The berry is characterized by much pigment under the skin. The fruit has a sprightly taste wholly free from any disagreeable foxiness. Rupestris under cultivation is said to be very resistant to rot and mildew of the foliage. The vine is considered hardy in the Southwest. The attention of hybridizers was attracted to this species over thirty years ago, and various hybrids have been produced of great promise for grape-breeding. The root system of Rupestris is peculiar in that the roots penetrate at once deeply into the ground instead of extending laterally as in other species. Like those of Vulpina, the roots are slender, hard and resistant to phylloxera. The species is easily propagated by cuttings. The vines bench-graft readily but are difficult to handle in field grafting.
4. _Vitis vulpina_, Linn. (_V. riparia_, Michx.). Winter Grape. River Grape. Riverside Grape. Riverbank Grape. Sweet-scented Grape.
Vine very vigorous, climbing. Shoots cylindrical or angled, usually smooth, slender; diaphragms thin; tendrils intermittent, slender, usually bifid. Leaves with large stipules; leaf-blade large, thin, entire, three- or lower ones often five-lobed; sinuses shallow, angular; petiolar sinus broad, usually shallow; margin with incised, sharply serrate teeth of variable size; light green, glabrous above, glabrous but sometimes pubescent on ribs and veins below. Cluster small, compact, shouldered; peduncle short. Berries small, black with a heavy blue bloom. Seeds two to four, small, notched, short, plump, with very short beak; chalaza narrowly oval, depressed, indistinct; raphe usually a groove, sometimes distinct. Very variable in flavor and time of ripening.