As you wander through campus in late fall, you may notice leafless shrubs with extremely showy bright red berries. These are the aptly-named winterberry hollies (Ilex verticillata). This upright, multi-stemmed shrub can reach about 10 feet tall, and has thin, smooth, grey bark. The glossy-red berries are round drupes about one-quarter inch in diameter that persist through the winter—actually starting out green and maturing to red in the fall.
The two- to three-inch long dark green leaves are alternate, simple, and lance shaped, with a sharply-toothed margin. The leaves turn yellow-green in fall, then blacken with frost and drop to reveal the berries. The plants are dioecious, meaning they are either male or female. Only female plants form berries, and they require a close-by male plant of the same species to set fruit. The small white flowers are not showy.
Winterberry hollies are native to our area, and to the whole eastern and central U.S. They like moist, acidic soils, including poorly-drained soils, and are often found at the edges of woods or in swamps, where they tend to sucker and form large clumps. They prefer full sun, and produce more berries with more sun, but will also tolerate shade. The berries are eaten by birds, and the plant is a larval host to the Henry's Elfin butterfly (Callophrys henrici).
In addition to the straight species, there are many beautiful cultivars of winterberry holly, including ‘Red Sprite’—a dwarf form that matures at three to four feet tall, and ‘Sparkleberry’—known for an abundance of berries that persist into spring.
To develop the above description, we used many sources, including Michael Dirr’s Manual of Woody Landscape Plants (Champaign, Illinois: Stipes Publishing, LLC, 1998), and the following websites: Dendrology at Virginia Tech (dendro.cnre.vt.edu/dendrology/main.htm), the University of Connecticut Plant Database (www.hort.uconn.edu/plants/), Wikipedia (www.wikipedia.org), and the Lady Bird Johnson Wildflower Center (www.wildflower.org).