Bittersweet (Celastrus sp.)
Bittersweet is a familiar autumn sight, clambering along fences and over stumps along roadsides. These woody vines are inconspicuous throughout the spring and summer, indistinguishable from many green-leafed twining plants in natural settings. In the fall their brilliant orange berries punctuate drab landscapes, adding a burst of color to the browns of falling leaves. Two types of this vine are commonly found in the United States. Oriental Bittersweet (Celastrus orbiculatus), originally from China, has made itself at home here and is the most common. The native American Bittersweet (Celastrus scandens) is the more desirable, but is fast disappearing from roadsides and woods in the eastern parts of North America. Both vines are tough, adaptable, long-lived and drought resistant.
Size: All bittersweets are twining vines, climbing by twisting their stems around some supporting structure. Typically oriental bittersweet will climb 20 to 30 feet if permitted. American bittersweet may reach 36 feet or so. These plants spread rapidly, American bittersweet being capable of adding up to 10 feet over one season. Pruning must control them.
Foliage: Bittersweet vines are deciduous, losing their leaves every fall when the colorful fruits appear. The leaves average 2 to 4 inches long and are green and oblong-oval in shape, with tapered tips. Those of oriental bittersweet are slightly more rounded and fatter than those of their American cousin, which more closely resemble peach leaves in shape. Leaves have finely toothed edges and are somewhat coarse in texture. Their undersides are slightly paler than their surfaces. They are a light yellow-green in the spring, darkening somewhat for summer and then turning bright yellow in the fall before they drop. American bittersweet leaves are slightly darker and glossier. These native vines are also generally less dense that oriental bittersweet, having fewer branches and less foliage.
Flowers and Berries: Male and female flowers are produced on separate plants in late May or early June after the leaves have emerged. Yellow green or green and inconspicuous, the tiny flowers appear in clusters about 3/8 inch wide. These clusters appear where the leaf stems join the vine all along the branches on oriental bittersweet vines. On American bittersweet vines, however, the flower clusters appear at the ends of vine branches. It is necessary to have both male and female plants in the area for pollination to take place, although a single male plant can pollinate several female ones. The flowers on female plants give way over the season to clusters of green, then red-orange fruits, which show from late September through December or later. Each is a yellow capsule about the size of a pea that splits open to display a red-orange flesh-covered seed inside. In American bittersweet these capsules droop from the tips of vine branches in clusters of 6 to 20. While all parts of bittersweet vines are poisonous to humans, the vines provide some food and effective cover to wildlife.