Frost Grape (Vitis vulpina)

Description: This deciduous woody vine is up to 60' long, branching occasionally. It frequently climbs up fences, shrubs, or trees using its tendrils, otherwise it sprawls across the ground. The base of a mature vine consists of a trunk up to 4" across, where the bark is dark gray-brown, coarse, and sometimes coated with lichens. On more slender woody branches, the grayish brown bark shreds easily, exposing light-colored wood underneath. Young shoots are light green, glabrous (or sometimes early-pubescent), and more or less terete, becoming slightly swollen at the nodes. The pith of branchlets is brown, while the diaphragms at the nodes of branchlets (where the pith is interrupted) are 2-5 mm. across. Alternate leaves occur along the branchlets and young shoots. The leaves are 3-6" long and 2½-4" across; they are cordate, orbicular-cordate, or ovate-cordate in shape, while their margins are coarsely and irregularly dentate. The leaves often lack lobes, although sometimes they have a pair of shallow lobes that resemble angular shoulders. The upper blade surface is medium green and glabrous, while the lower blade surface is light green and either entirely glabrous or it may have short hairs along the major veins. The slender petioles are 2-4½" long, light green to reddish brown, and usually short-pubescent; less often they are glabrous. Across from the petioles of two-thirds of the leaves, there are either branched tendrils or flowers/fruit. These tendrils or flowers/fruit are opposite from consecutive pairs of leaves, but they are absent for every third leaf; tendrils are more common than flowers/fruit. The tendrils are light green, slender, glabrous, and branched; their tips often twine about adjacent objects, providing support for the vine.

Panicles of yellowish green flowers up to 7" long and 3½" across are occasionally produced; these panicles are narrowly pyramidal in shape, although they often nod or hang downward from their peduncles (basal stalks). The flowers can be perfect or unisexual (either male or female); individual flowers are about 3 mm. (1/8") across. Each perfect flower has 5 petals that are early-deciduous, an insignificant calyx that has been reduced to a flat disk, 5 stamens with white filaments and yellow anthers, and a pistil. Male flowers lack pistils, while female flowers lack fully developed stamens, otherwise they are the same as perfect flowers. The branches and pedicels of panicles are light green or yellowish green, glabrous or finely hairy, and terete. The peduncles are 1-6" long; they are similar to the branches and pedicels of panicles in their characteristics. The blooming period occur from late spring into early summer, lasting about 1-2 weeks. The flowers have a strong sweet fragrance. Afterwards, panicles with perfect or female flowers are replaced by berries, although it is not uncommon for these fruits to abort. Initially, these berries are small and green, but they become dark blue-violet or black and 6-8 mm. across at maturity during the autumn. Mature berries are globoid in shape and they may, or may not, have a glaucous bloom. The interior of these berries is juicy with a sour to sweet-tart flavor; they become sweeter after there has been a light frost. Each berry contains about 2-4 seeds; individuals seeds are grayish brown to dark brown, ovoid in shape, and 3-5 mm. long. The root system is woody and spreading. This vine reproduces by reseeding itself.

Cultivation: The preference is full sun to light shade, moist to mesic conditions, and a fertile loamy soil, although other soil types are tolerated. This woody vine can become aggressive, climbing over shrubs and small trees and killing them. It is winter cold-hardy to about Zone 4 or Zone 5 in North America, as defined by the USDA.

Range & Habitat: The native Frost Grape (Vitis vulpina) is occasional throughout Illinois, although it is slightly less common in the northern one-third of the state than elsewhere (see Distribution Map). Habitats include floodplain woodlands, banks of rivers and streams, woodland openings, woodland borders, thickets, and fence rows. Disturbance that reduces the overhead canopy of trees encourages the development of this vine because of the increased levels of light. It is an early colonizer of such disturbance-caused openings.

Faunal Associations: In general, the value of the Frost Grape (Vitis vulpina) and other wild grapes (Vitis spp.) to wildlife is quite high. Robertson (1929) observed honeybees, bumblebees, and long-horned bees (Synhalonia) visiting the flowers of Frost Grape, where they collected pollen. Other insects feed on the leaves, bore through the wood, and feed on other parts of these woody vines. Examples include the Grape Flea Beetle (Altica chalybea), Grape Rootworm (Fidia viticida), Grapevine Aphid (Aphis illinoisensis), Marmorated Stink Bug (Holcostethus limbolarius), larvae of gall flies (Schizomyia spp.), and leaf-mining larvae of a Heliozelid moth (Antispila viticordifoliella). Other insect feeders include leafhoppers (Erythroneura spp.), spittlebugs (Aphrophora spp.), plant bugs (Miridae), adults of Scarab beetles, wood-boring larvae of long-horned beetles (Cerambycidae), larvae of weevils, and larvae of Sphinx moths. More complete lists of these species can be found in the Moth Table, Leafhopper Table, and Insect Table. The fruit of wild grapes are an important source of food for many kinds of birds, especially for woodland songbirds and some upland gamebirds. These species include various thrushes (Cartharus spp.), Northern Flicker, Common Grackle, Catbird, American Robin, Northern Cardinal, Eastern Kingbird, Great Crested Flycatcher, Fox Sparrow, Bobwhite Quail, Wild Turkey, and Wood Duck. The Bird Table has a more complete list of these species. Mammals that eat the fruit of wild grapes include the Black Bear, Gray Fox, Red Fox, Raccoon, Opossum, Striped Skunk, Fox Squirrel, and Gray Squirrel. By eating the seed-bearing fruits, these animals spread wild grapes into new areas. The White-tailed Deer browses primarily on the leaves and young branches of these woody vines, while the Cottontail Rabbit browses on the foliage and gnaws on the bark (Barnes, 1999; Martin et al., 1951/1961; Beeman & Pelton, 1980). In addition to birds and mammals, the fruit of wild grapes is a source of food for the Eastern Box Turtle (Ernst et al., 1999). Because of the dense network of branches and leaves that these woody vines often create, they provide excellent cover and nesting habitat for songbirds and many other kinds of wildlife.

Photographic Location: Along a fence row near the edge of a woodland at Crystal Lake Park in Urbana, Illinois.

Comments: The Frost Grape (Vitis vulpina) is one of several native wild grapes that can be found in Illinois. It can be distinguished from similar species of grapes (Vitis spp.) primarily by the lack of significant lobes on most of its leaves, and its leaf undersides are either hairless or they have hairs along the primary veins only. Frost Grape could be confused with Raccoon Grape (Ampelopsis cordata), however the latter species has branchlets with uninterrupted pith, branchlets with tight bark, undivided tendrils, and panicles of fruits that are as wide or wider than they are long. In contrast, wild grapes have branchlets with interrupted pith, branchlets with loose and shredded bark, divided tendrils, and panicles of fruits that are longer than they are across. Frost Grape also has wider diaphragms at the nodes of its branchlets (where the pith is interrupted) as compared to the similar Riverbank Grape (Vitis riparia); the diaphragms of Frost Grape are 2-5 mm. across, while the diaphragms of Riverbank Grape are 0.5-1.5 mm. across. The teeth along the leaf margins of Riverbank Grape tend to more acute, and its leaves are more likely to have significant lobes. Other common names of Vitis vulpina include Fox Grape and Chicken Grape. However, Fox Grape more often refers to another species of grape, Vitis labrusca. The range of this latter species occurs to the east of Illinois. An obsolete scientific name for the Frost Grape is Vitis cordifolia.