Riverbank Grape is a perennial climbing woody vine with tendrils to help in climbing. Given the right conditions, the vine can grow to 50 feet long. It can do this by climbing tree trunks to reach the tree canopy. If a vine develops in the canopy of a tree or shrub, the shading caused by the grape leaves will eventually kill the host plant.
Stems: Older stems are gray or brown and become woody and reddish-brown with shaggy bark shedding in long thin strips on old growth. Young stems are yellow-green to reddish in color, smooth and sometimes with a powdery bloom. Tendrils are opposite most leaves but commonly missing at every third leaf node and at nodes that have a flower panicle. The growing tip of a stem is protected by a pair of unfolding leaves.
Leaves are green to yellowish on top, alternate, egg shape with heart shaped bases, sharply three-lobed (sometimes more, but extra lobes may not be as noticeable), coarsely and sharply toothed, pale green and smooth under, although young leaves can have fine hair under which recedes to remain just on the margins and the mid-veins. Each leaf has a long stalk (petiole) that can be reddish in color. At the leaf nodes the stems tend to enlarge. Fall color is yellow. The termination of the stem has a pair of leaves, instead of tendrils.
Inflorescence: The flowers are in thyrses, 2 to 5 inches in width, usually elongated and drooping after the fruit forms. They appear opposite the leaves on the current year's growth except for every third leaf. A thyrse is a branched inflorescence in which the main axis is indeterminate (it has no growth stopping point) and the lateral branches determinate (they have limited growth).
Flowers: Flowers are functionally separate. The male flowers have 5 extended erect stamens with 5 nectary glands alternating; the female flowers have a well developed pistil, a short style and 5 short function-less stamens (staminodes). The 5 tiny petals are greenish-yellow in color. The calyx is minute.
Fruit: Mature fruit is a bluish black berry, 1/4 to 3/8 inch in size and will usually have a whitish bloom; they hang in drooping clusters. Some consider the fruit bitter and only turning sweet after a frost. I find that berries with bloom in late fall are tasty. Each berry contains 1 to 4 reddish-brown egg-shaped seeds, flattened on one side, 5 to 6 mm long.
Habitat: River-bank Grape is commonly found in floodplain forest, wooded swamps and marshes, fence rows, even drier sites where it can get climbing support; full sun is preferred, light shade is tolerated. It can be invasive and in Ohio it is considered a prohibited noxious weed. Many insects (including Japanese Beetle) and caterpillars feed on the leaves and by mid summer damage can frequently be quite noticeable. Leaf galls also form. The plant can be propagated by cuttings taken before the early blooming period or by seeds that have had a long cold stratification.
Names: The genus Vitis, is the Latin name for 'grape vines'. The current species name riparia, is from the Latin referring to 'banks of rivers'- leading to the 'riverbank' in the common name. The author name for the plant classification - “Michx.” is for Andre Michaux (1746-1802), French botanist who made many exploring expeditions in the U.S. collecting and cataloging many species. Two important works of his are the Histoire des chênes de l'Amérique septentrionale (1801 - Oaks of North America), and the Flora Boreali-Americana (2 vols., 1803, published posthumously, containing this species' description). His son Francois, traveled with him and the father’s notes were later used for the 3-volume North American Sylva.
Over the years several subspecies of V. vulpina, the Frost Grape, have been reclassifed as V. riparia and now V. vulpina stands alone as a separate species without subspecies or varieties. There are today no accepted varieties of V. riparia.
Comparisons: The only other wild grape recognized in Minnesota is Vitis aestivalis var. bicolor, the Silverleaf or Summer grape and it is found in the wild only in Houston, Winona and Wabasha counties. It has more whitened leaf undersides. In neighboring states to the south and east the Frost Grape grows, V. vulpina. That species has stem growing tips not enveloped by a pair of unfolding leaves and the berries are usually without any whitish bloom.
Above: 1st photo - Flower Clusters appearing opposite the leaves on new growth (note: except every third leaf); shown here with the first flowers opening. 2nd photo - Mature fruit clusters with the characteristic whitish bloom.
Below: 1st photo - Flower clusters forming opposite the leaf nodes on new growth. Note that the end of the stem always has a pair of leaves. 2nd photo - A typical leaf with three main pointed lobes on a reddish young stem.
Below: 1st photo - Note that the tendrils also arise at a node opposite a leaf except where flower clusters arise. 2nd photo - Leaves can be seriously attacked by leaf galls.
Below: The flower sexes are functionally separate - Female flowers 1st photo with the ovary and sterile stamens (staminodes ; 2nd photo - male flowers with five stamens.
Below: Fruit Development: 1st photo - green fruit of mid-summer. 2nd photo - Mature fruit of autumn with the characteristic whitish bloom. Birds will devour most fruit before winter.
Below: 1st photo - Each berry contains 1 to 4 reddish-brown egg-shaped seeds, flattened on one side, 5 to 6 mm long. 2nd photo - The underside of young leaves will frequently have fine hair which with age, recedes to the ribs.
Below left: 1st photo - Old stems have shaggy bark shedding in long thin strips on old growth as these climbing on a tree show. 2nd photo - This tree has several vine stems climbing on it including one wrapping around the others.
Below: Large sections of the fencing in the Upland Garden are covered with Wild Grape vines, with a few Moonseed plants interspersed.
Notes: Riverbank Grape is native to much of the U.S. except states in the SW and the far south. It is also native to the lower Canadian provinces from Manitoba eastward. In Minnesota it is found in almost all counties except 18 that are widely scattered in the western half of the state and Lake County in the Arrowhead. Eloise Butler cataloged the plant on April 29, 1907 as V. vulpina, and also when she planted the species in 1922. As only V. riparia is indigenous to the Garden area it is probable she was finding one of the former species of V. vulpina that are now classified as V. riparia. She obtained the 1922 plants from the Park Board Nursery so it is likely that they too were V. riparia. Martha Crone planted it in 1947 when she was developing the Upland Garden and listed it on her 1951 census as V. riparia.
Uses: Extensive use of wild grapes has been made for jellies and wine. Mature wild grapes can make jelly if you follow the recipe for cultivated grapes and add pectin. HOWEVER, the berries have a lot of pulp and most of the space is occupied by the seeds, so you will need a lot of berries to make 8oz of jelly.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"