Summer Grape (Vitis aestivalis aestivalis)

Description: This woody climbing vine is up to 35' in length (rarely longer), branching occasionally. By means of its twining tendrils, this vine has the capacity to climb adjacent vegetation and fences. On older vines, the trunk is woody and up to 6" across; the gray to reddish brown bark peels into long shredded strips. Older branches have bark that is similarly colored, but more smooth. Young non-woody branches are light green, yellowish green, or reddish green; they are terete to angular and sparsely to moderately covered with white hair, but become glabrous later. The pith of branches is brown; at the swollen nodes of the branches, this pith is interrupted by a thin white partition about 2 mm. or more across. Alternate deciduous leaves occur along non-woody branches. Except for every third leaf along the vine, there is a branched tendril or inflorescence that is opposite from each leaf. Individual leaves are 3-8" long and similarly across; they are orbicular to oval with 3 or 5 palmate lobes, while their margins are dentate. The palmate lobes vary from shallow to deep. When the lobes are deep, they form narrow sinuses with rounded bottoms (rather than sharply cleft bottoms). On each vine, at least some leaves will have deep lobes. The upper leaf surface is dull medium green and hairless to slightly hairy, while the lower leaf surface is pale green and moderately covered with appressed woolly hairs that are white to light brown. The petioles of the leaves are 3-6" long, rather angular, and usually hairy.

The greenish yellow flowers are produced in panicles about 2-5" long. These flowers can be either unisexual (male or female) or perfect. Individual flowers are about 1/8" (3 mm.) across, consisting of 5 deciduous petals, an insignificant calyx that has been reduced to a flat disk, and the reproductive organs. Male flowers have 5 prominent stamens, while female flowers have a superior ovary with a short style. Perfect flowers have both types of reproductive organs. The blooming period occurs during late spring and lasts about 1 week. The flowers are quite fragrant. Fertile female flowers are replaced by berries that are arranged in panicles about 3-8" long. These panicles are usually wider near their bases than toward their tips. After they become mature during late summer or autumn, individual berries are ¼-½" across, globoid in shape, dark blue to black, and slightly glaucous. Each berry has a juicy interior with 2-4 small seeds. The flavor of mature berries varies from sweet to tart.
Distribution Map

Cultivation: This woody vine prefers full to partial sun, moist to dry-mesic conditions, and soil containing loam, sandy loam, or some rocky material. It will also grow on clay soil if it is adequately drained. This vine can smother and even kill shrubs and small trees. Production of berries requires some exposure to sunlight.

Range & Habitat: The native Summer Grape is occasional to locally common in southern and central Illinois, while in the northern section of the state it is less common or absent. This map combines the distribution of both the typical variety of Summer Grape, as described here, and Vitis aestivalis bicolor (Silver-Leaved Grape), which is found primarily in NE Illinois. Habitats for Summer Grape include upland woodlands, sandy upland woodlands, typical savannas and sandy savannas, openings in bottomland woodlands, woodland borders, thickets, powerline clearances in wooded areas, areas along woodland paths, fence rows, limestone glades, and thinly wooded bluffs. Wooded habitats are dominated by various deciduous trees. Summer Grape prefers areas where there has been some history of disturbance such as wildfire, logging, etc., as it is intolerant of dense shade from overhead canopy trees.

Faunal Associations: The flowers are cross-pollinated by bumblebees (Bombus spp.), honey bees (Apis mellifera), long-horned bees (Synhalonia speciosa), and probably other bees (see Robertson, 1929). In addition to these floral visitors, many insects feed on various parts of Summer Grape and other wild grapes. These species include Daktulasphaira vitifoliae (Grape Phylloxera), which forms galls on the leaves and roots; Cecidomyia viticola (Grape Gall Midge) and Lasioptera vitis (Grapevine Tomato Gall Midge), which form galls on the leaves or tendrils; the caterpillars of Geina periscelidactyla (Grape Plume Moth), Dyspteris abortivaria (The Bad Wing), Eumorpha achemon (Achemon Sphinx), and many other moths (see Moth Table); Piesma cinerea (Ash-Gray Leaf Bug sp.), which feeds on the leaves and flowers; the plant bugs Paraxenetus guttulatus and Taedia scrupea; the aphid Aphis illinoisensis, which sucks juices from new leaves and shoots; Eratoneura tricincta (Three-Banded Leafhopper), Erythroneura comes (Grape Leafhopper), and many other leafhopper species (see Leafhopper Table); Heterothrips vitis (Grape-Bud Thrips) and Drepanothrips reuteri (Grape Thrips); Altica chalybea (Grape Flea Beetle) and Colaspis brunnea (Grape Colaspis), which feed on the foliage; larvae of the long-horned beetles Clytoleptus albofasciatus (Grape Trunk Borer) and Saperda puncticollis (Woodbine Borer), which bore through the wood of dead and dying vines; and larvae of the weevil Ampeloglypter ater (Grape Cane Girdler), which bore into new shoots. The Insect Table has a more complete list of these species.

Summer Grape and other wild grapes are also valuable to various vertebrate animals. Many gamebirds and songbirds eat the berries (see Bird Table), as do such mammals as the Black Bear, Coyote, Red Fox, Gray Fox, Fox Squirrel, Gray Squirrel, Raccoon, Opossum, and Striped Skunk. The Eastern Box Turtle also eats the fallen or low-hanging berries of wild grapes. These animals help to spread the seeds into new areas. Many birds like to nest in the cover that is provided by the tangled vines of Wild Grape, and some of these birds use the shaggy strips of bark in the construction of their nests; these species include the Cardinal, Catbird, Brown Thrasher, Northern Mockingbird, Red-Eyed Vireo, and Yellow-Breasted Chat. Even the Red Squirrel, Deer Mouse, and White-Footed Mouse sometimes construct nests in the ascending vines of wild grapes.

Photographic Location: A powerline clearance and roadside along Busey Woods in Urbana, Illinois.

Comments: This is one of several native Vitis spp. (Wild Grapes) that can be found in Illinois. The typical variety of Summer Grape, as described here, can be distinguished from other wild grapes within the state by using the following two criteria: 1) the leaves often form lobes with deep narrow sinuses that have rounded bottoms, and 2) the lower surface of the leaves is covered with woolly appressed hairs that are dull white to light brown. Another variety, Vitis aestivalis bicolor (Silver-Leaved Grape), which is also native to Illinois, differs from the typical variety by having leaf undersides that are bright white, glaucous, and hairless. It is also more glabrous overall and often has bright red stems. Another wild grape, Vitis cinerea (Winter Grape), also has leaf undersides with woolly appressed hairs, but they are more dense and bright white (at least while young), and the leaves of Winter Grape never have deep lobes. Other species of wild grapes in Illinois have glabrous leaf undersides, or their leaf undersides have hairs along the veins only.