Bad Berries: Learn to Identify 8 Invasive Plants by Their Winter Berries

Identifying invasive plants is not always easy. But winter brings helpful clues to the branches of some habitat-altering vines and shrubs: berries. At least, that’s what most of us call them (botanically, these fruits may be pomes, drupes, or arils). With fruit persisting from fall into deep winter, many of these plants are carried further afield by birds who feed on them in the lean season. Some of these invasive plants have become so problematic that individual states have banned their sale. Despite that, some persevere in public plantings and (perversely) in botanical gardens, where they now seem like relics of an age of innocence, when exotic plant collections were tended without a thought as to how they might change the broader landscape and the biological livelihood of a place to which they are native.

In time for a horticultural New Year’s resolution, here are eight bad berries: Don’t plant these invasive plants, and if you have the means, control or remove them.

Photography by Marie Viljoen.

1. Privet

Usually seen in the form of a tidily clipped privacy-hedge, privet is the common name of several species of Ligustrum, but often refers to Ligustrum sinense, or Chinese privet, introduced to the United States from East Asia. Because its fruits (drupes, botanically) are relished by birds, the shrubs have escaped cultivation and these invasive plants have spread—especially in the Southern US and in the Northeast, where they form dense thickets that crowd out native plants. If you must keep a privet hedge, shear off its fruit in late fall or early winter.

2. Asian Bittersweet

As invasive plants go, these vines can be vexing, because the native and invasive species of bittersweet look very similar. The American species, Celastrus scandens, bears its berry-like arils only in terminal clusters (meaning at the end of each branch), whereas the fruit of Asian bittersweet (C. orbiculata) appears in leaf axils, all along each branch. Bittersweet climbs trees and shrubs, adding so much weight that it can break them. As it twines, it girdles trunks and branches.

3. Burning Bush (or Winged Euonymus)

You can see why it is loved: In fall, the leaves of burning bush (also known as winged Euonymous because of the thin ridges on its branches) blaze scarlet. When its arils pop open, they reveal vividly orange seeds, which birds eat happily. Euonymous alatus has spread widely into woodlands where it alters their ecology by displacing native plants. Do not plant it, do not sell it, and if you remove it, choose a native shrub like winged sumac (Rhus copallinum) to replace it.

4. Jetbead

Their white flowers are lovely in mid-spring, resembling mock orange, but black jetbead shrubs create a dense understory in woodlands, preventing the development of native seedlings, and—we’ll say it again—altering the local ecology. The glossy fruit are drupes held in clusters of two to four, and resemble minimalist blackberries.

5. Japanese Honeysuckle

At summer’s end the small, plump berries of sweetly-scented Japanese honeysuckle (Lonicera japonica) begin to ripen, just in time for migration. The aggressive vines twine up shrubs and trees, girdling them as they grow. Japanese honeysuckle creates shaded top-heavy layers that hinder the growth of smaller plants, below. While we love foraged honeysuckle flowers for making honeysuckle cordials and vinegars, this is not a vine to plant. Choose a native species, instead.

6. Barberry

Tick hotels. Do we need to say more? Studies have shown that the density of ticks sees a distinct uptick (sorry) where barberry flourishes. European and Japanese barberries are both invasive and have been banned for sale in numerous states.

7. Multiflora Rosehips

Thousands of tiny multiflora rosehips ripen in early fall and are relished by small mammals and birds. The seeds have a very high germination rate. Like barberry, multiflora rose has invaded woodlands, where it forms dense, excluding thickets.

8. Nandina (or Heavenly Bamboo)

Long appreciated for its handsome winter berries, Nandina domestica has become invasive beyond its garden confines. In the Southeast especially, it has invaded woodlands, contributing to the loss of biodiversity. Interestingly, under certain circumstances, Nandina berries are toxic to birds like cedar waxwings, who gorge on them early in the season when they release higher levels of cyanide. Older fruit is less cyanogenic, and birds who eat only a berry or two are not affected. (The leaves also contain high levels of cyanide, which is released when they are chewed, or crushed.)

See also:

• Wineberries: Invasive—But Delicious to Eat and Drink
• What’s that Berry? Test Your Knowledge of Fall’s Red Fruits
• Get Twiggy with It: 7 Favorite Shrubs with Winter Blooms and Berries