7. _Vitis æstivalis_, Michx. Blue Grape. Bunch Grape. Summer Grape. Little Grape. Duck-shot Grape. Swamp Grape. Chicken Grape. Pigeon Grape.
Vine very vigorous, shoots pubescent or smooth when young; diaphragms thick; tendrils intermittent, usually bifid. Leaves with short, broad stipules; leaf-blade large, thin when young but becoming thick; petiolar sinus deep, usually narrow, frequently overlapping; margin rarely entire, usually three- to five-lobed; teeth dentate, shallow, wide; upper surface dark green; lower surface with more or less reddish or rusty pubescence which, in mature leaves, usually shows in patches on the ribs and veins; petioles frequently pubescent. Clusters long, not much branched, with long peduncle. Berries small, with moderate amount of bloom, usually astringent. Seeds two to three, of medium size, plump, smooth, not notched; chalaza oval, distinct; raphe a distinct cord-like ridge. Leafing and ripening fruit late to very late.
The division of the original species has reduced the habitat materially, confining it to the southeastern part of the United States from southern New York to Florida and westward to the Mississippi River. Æstivalis grows in thickets and openings in the woods and shows no such fondness for streams as Vulpina, or for thick timber as Labrusca, but is generally confined to uplands. Under favorable circumstances, the vines grow to be very large. Æstivalis is preëminently a wine grape. The fruit usually has a tart, acrid taste, due to the presence of a high percentage of acid, but there is also a large amount of sugar, the scale showing that juice from this species has a much higher percentage of sugar than the sweeter-tasting Labruscas. The wine made from varieties of Æstivalis is very rich in coloring matter and is used by some European vintners to mix with the must of European sorts in order to give the combined product a higher color. The berries are destitute of pulp, have a comparatively thin, tough skin and a peculiar spicy flavor. The berries hang to the bunch after becoming ripe much better than do those of Labrusca.
This species thrives in a lighter and shallower soil than Labrusca and appears to endure drought better, although not equaling in this respect either Vulpina or Rupestris. The French growers report that Æstivalis is very liable to chlorosis on soils which contain much lime. The leaves are never injured by the sun and they resist the attacks of insects, such as leaf-hoppers, better than any other American species under cultivation. Æstivalis is rarely injured by black-rot or mildew, according to American experience, but French growers speak of its being susceptible to both. The hard roots of Æstivalis enable it to resist phylloxera, and varieties with any great amount of the blood of this species are seldom seriously injured by this insect. An objection to Æstivalis, from a horticultural standpoint, is that it does not root well from cuttings. Many authorities speak of it as not rooting at all from cuttings, but this is an over-statement of the facts, as many of the wild and cultivated varieties are occasionally propagated in this manner, and some southern nurseries, located in particularly favorable situations, make a practice of propagating it by this method. Varieties of this species bear grafting well, especially in the vineyard.