Vitis riparia

Riverbank grape’s flowers develop in 5″ long, drooping, cylindrical or pyramidal panicles opposite the leaves of new branches (but skipping every third leaf). The flowers are greenish-yellow and are best described as skeletal; they may be either unisexual or (rarely) perfect (both male and female reproductive organs functional). The male and female unisexual flowers usually both occur on the same plant, either in separate or mixed clusters; both male and female flowers are 1/8″ across or less, with a minute calyx and five green to yellowish petals that quickly fall off. Male flowers have five very long, pale, erect stamens around a button-like center; female flowers have an ovary with a short style and five short, sterile stamens, often contorted. The fruit are …. grapes — a round berry, 1/4-1/2″ across containing 1-4 seeds, initially green but turning blue-black as it matures, often with a white bloom on the skin. You know, grapes. The fruit of riverside grape is often sour until after a frost, then becomes more “sweet/tart” to the tongue. Riverbank grape is subject to parasitism by the grape filbert gall midge (Ampelomyia vitiscoryloides), an insect whose larvae produce large, very hairy, conical galls at leaf nodes. This gall midge is restricted to the eastern half of North America; it was first described by Alpheus Spring Packard, Jr. in 1869.

Riverbank grape is a native perennial vine that can grow up to 50 feet long. It can climb surrounding vegetation and structures using its tendrils but can only rise a few feet off the ground without external support. The woody main stem branches occasionally and is covered with brown, shaggy bark; the smaller, non-woody stems are yellowish-green to red, hairless, and sometimes are covered with a waxy bloom. The stems become somewhat wider at leaf nodes (where a thin partition is present across the pith). The tip of an actively growing stem is covered by a pair of young leaves. The alternate leaves are roughly heart- or disc-shaped overall, 4-8″ long and nearly as wide, palmately lobed, (usually) with three clear lobes; the spaces between the lobes may be broad and shallow or narrow and U-shaped. The upper leaf surface is yellowish green and hairless while the underside is pale green with hairs along the main veins; the leaf margins are coarsely serrated with protruding hairs. The leaf petioles are about 3″ long and slender, usually pale green to red and hairless.

Riverbank grape is a native perennial vine that can grow up to 50 feet long. It can climb surrounding vegetation and structures using its tendrils but can only rise a few feet off the ground without external support. The woody main stem branches occasionally and is covered with brown, shaggy bark; the smaller, non-woody stems are yellowish-green to red, hairless, and sometimes are covered with a waxy bloom. The stems become somewhat wider at leaf nodes (where a thin partition is present across the pith). The tip of an actively growing stem is covered by a pair of young leaves. The alternate leaves are roughly heart- or disc-shaped overall, 4-8″ long and nearly as wide, palmately lobed, (usually) with three clear lobes; the spaces between the lobes may be broad and shallow or narrow and U-shaped. The upper leaf surface is yellowish green and hairless while the underside is pale green with hairs along the main veins; the leaf margins are coarsely serrated with protruding hairs. The leaf petioles are about 3″ long and slender, usually pale green to red and hairless. The flowers develop in 5″ long, drooping, cylindrical or pyramidal panicles opposite the leaves of new branches (but skipping every third leaf). The flowers are greenish-yellow and are best described as skeletal; they may be either unisexual or (rarely) perfect (both male and female reproductive organs functional). The male and female unisexual flowers usually both occur on the same plant, either in separate or mixed clusters; both male and female flowers are 1/8″ across or less, with a minute calyx and five green to yellowish petals that quickly fall off. Male flowers have five very long, pale, erect stamens around a button-like center; female flowers have an ovary with a short style and five short, sterile stamens, often contorted. The fruit are …. grapes — a round berry, 1/4-1/2″ across containing 1-4 seeds, initially green but turning blue-black as it matures, often with a white bloom on the skin. You know, grapes. The fruit of riverside grape is often sour until after a frost, then becomes more “sweet/tart” to the tongue.

Riverbank grape is subject to parasitism by the grape filbert gall midge (Ampelomyia vitiscoryloides), an insect whose larvae produce large, very hairy, conical galls at leaf nodes. This gall midge is restricted to the eastern half of North America; it was first described by Alpheus Spring Packard, Jr. in 1869.