American bittersweet

not listed

N5 - Secure

SNR - Unranked

not listed

UPL - Obligate upland

FACU - Facultative upland

FACU - Facultative upland

American bittersweet is a perennial woody vine that rises from a woody taproot. It is usually found climbing on a tree or other adjacent vegetation. It can climb up to 65′. Occasionally it appears as a low shrub or sprawls on the ground.

Stems are green and hairless in the first year, becoming gray or brown in the second year. They do not have tendrils or aerial roots. They climb by growing spirally (twining) from left to right (dextrorsely). Older stems eventually become woody and get up 2¾″ in diameter at the base. The branches are circular in cross section and are not winged.

The bark on young woody stems is thin and brown. On mature stems the bark is light gray and rough with corky, diamond-shaped ridges. The bark on older stems is smooth and peels off in flakes (exfoliates).

The leaves are alternate and deciduous. They are variable in shape, even on the same stem. When they first appear and begin unfolding each side of the blade is rolled inward toward the upper side. Young leaves are yellowish-green and have a long drawn out tip. Mature leaves are on ⅜″ to 1″ long leaf stalks. The leaf blades are elliptic, elliptic egg-shaped, or inversely egg-shaped; 2″ to 4¼″ long; and 1″ to 2⅜″ wide. They are often at least than 2 times as long as wide. They are rounded to angled or short tapered at the base, and usually tapered to a sharp point at the tip with curved sides along the tip. The leaf tip is often ⅝″ long or longer. Sometimes the leaf blades are rounded at the tip. The upper surface is green or dark green and hairless. The lower surface is paler green and hairless. The margins are finely toothed with rounded or incurved teeth. The teeth have small gland at the tip. The leaves turn greenish-yellow to yellow in the fall.

The inflorescence is an elongated, ¾″ to 2⅜″ long, branched cluster (panicle) of 5 to 60 flowers at the end of each stem branch. The flowers mature from the bottom up.

Male and female flowers are similar and are borne on separate plants. Each flower is about ¼″ across and has 5 sepals and 5 petals. The sepals are green and 1⁄32″ to 1 ⁄16″long. The petals are pale green or greenish white, about ⅛″ long, and 1⁄32″ to 1 ⁄16″wide.

Male flowers have 5 stamens and a small, nonfunctioning (vestigial) pistil. The stamens have white filaments the anthers have white pollen. Female flowers have a functioning pistil and 5 vestigial stamens (staminodia). The style is stout and has a 3-lobed stigma at the tip.

The fruit is a more or less globe-shaped, ¼″ to ½″in diameter, 3-lobed capsule. The capsule is green at first, turning bright orange at maturity. It matures in early September to early October. At that time the it splits open into three parts and folds back revealing 3 to 6 bright red, berry-like seed coatings (arils). Each aril contains a single brown seed. The fruits remain on the vine through the winter. They are poisonous to humans but not to birds.

Climbing, up to 65′ in length

Pale green or greenish white

Moist to dry. Thickets, upland woodlands, woodland edges and openings, and roadsides. Partial shade.

Mid-May to late June

Sources

2, 3, 4, 5, 7, 8, 22, 24. 28, 30.

Native

Widespread and fairly common

Vine

Leaves

Location: Grey Cloud Dunes SNA

Location: Crow-Hassan Park Reserve, Hennepin County