American bittersweet is a native, twining woody vine that climbs into trees to heights of 20 feet or, more commonly, sprawls on bushes or fences. Its clusters of orange fruits split into sections to reveal seeds covered with a bright red, fleshy coating.
Leaves are alternate, simple, with the blade 2–4 inches long, 1–2 inches wide, egg-shaped to oval to lance-shaped, tip pointed, the base ending at a sharp angle or rounded, the margin entire or with small, finely pointed teeth; the upper surface is dark yellowish green, smooth; the lower surface is paler, smooth; the leaf stalk is about ½ inch long, smooth.
Stems are spreading to twining, green to gray or brown; tendrils absent.
Bark is light brown, smooth, with prominent pores; the bark of old stems peels into thin flakes and small sheets; the wood is soft, porous, white.
Flowers May–June, in clusters of numerous flowers at the end of twigs; male and female flowers are in separate clusters; plants usually with mostly female or male flowers only.
- The male flowers are in clusters about 2 inches long; the flower stalks are about 1 inch long; flowers are small, inconspicuous, greenish white to yellow; petals 5; stamens 5, shorter than the petals.
- The female flowers are in clusters 1–1½ inches long; the flower stalks are 1¼–2 inches long; flowers are small, 5–25, greenish white to yellow; petals 5; stamens 5, poorly developed.
Fruits in July–October, in hanging clusters 2½–4 inches long; fruits 6–20, globe-shaped, about ¼ inch across, fruit orange to yellow, leathery, splitting into 3 sections, each section with 1 or 2 globe-shaped seeds; seeds covered with a bright red, fleshy coating, persistent and showy in autumn; seeds white at first, then cream-colored and drying to brown, oval, about ¼ inch long.
Similar species: Round-leaved bittersweet, or Asiatic or oriental bittersweet (C. orbiculatus), is closely related but is native to Asia and can aggressively escape from cultivation. It is fast becoming a serious weed in the eastern United States. Its fruits are not as showy as our native American bittersweet; prior to splitting open, the fruits are orange-yellow to orange (not orange to red) and are single or in smaller clusters. Its leaves are fairly circular (about as wide as they are long) or are broadest above (not below) the middle. Leaf margins have small, rounded (not finely pointed) teeth. Flower/fruits are axillary (arising along the stems in the leaf axils), in clusters of 2–4.
Other plants in the same family (sharing the same basic fruit structure) include our native eastern wahoo, strawberry bush, and running strawberry bush, and the nonnative invasive burning bush (winged euonymus) and wintercreeper.