Posted: May 28, 2021
Japanese barberry and burning bush are two common shrubs that are invasive.
Japanese barberry is commonly sold in the nursery industry but is known to take over forest land.
How often have I heard "it's not invasive in my garden" or "I haven't seen it escape into my neighborhood." Do we see the seeds of an invasive plant blow in the wind? Where do they go? Those seeds will settle in a location far from our eyes and away from our homes. Where has the wind taken those seeds? Where have the seeds drifted through rain gutters to stop in some swampy wet area just perfect for germination, where over time these seeds turn into healthy plants? Their roots begin to spread to the point that they become aggressive, taking over native plants that are naturally controlled by our native predators. Under these circumstances, invasive species take away habitat for our native insects, rodents, ducks, or other wildlife that would typically breed, feed and live with our native plant material but now are dying because they can't survive in this newly-introduced habitat.
Many of us have heard about lythrum, or purple loosestrife. We know how it has taken over wetlands in New England and is threatening and destroying them here in our state. But do we know about Japanese Barberry - Berberis thunbergii and Burning bush - Euonymus alatus? These are just two common plants grown and sold in the nursery industry. None of these plants are illegal to sell in Pennsylvania, and they have not been listed on the noxious week list. However, Pennsylvania does have them listed on the invasive plant list. Why? Because they are now found in our woodlands, in our meadows, and along the edges of forests, degrading our natural habitats and replacing our native species.
Japanese barberry (Berberis thunbergii)
is also commonly sold in the nursery industry. This plant is native from southern Europe to central China. It is very easily propagated from seed and very adaptable to many growing conditions. The seeds from some of the selected varieties of the species, such as Crimson Pygmy, will revert back to B. thunbergii, making them invasive plants for our landscape and our community. Its adaptability to many soils, lack of specific moisture requirements, tolerance to sun or lack of sun, and viability of the seeds makes this a plant to avoid. If allowed, it will replace many of our native plants that live in the shrub layer of the forests and will shade many plants on the forest floor, causing them to die and thus reduce biodiversity.
There are many native plant replacements. For instance, Itea virginica or sweetspire, is a native plant offering a beautiful red fall color. It has drooping white flowers in late spring, early summer. Selected varieties are available at local nurseries. Another substitution is the red chokeberry, Aronia arbutifolia. This native shrub will tolerate a wide range of soil types from wet to well-drained soils and grow in sun to part shade. Red berries replace the spring flowers in late summer and stay on the branches well into the winter. The birds will eventually eat the berries, but they are some of the last to go because of the tartness and bitterness of the fruit. This plant gets a beautiful red fall color, and selected varieties are available in local nurseries.
Burning Bush (Euonymus alatus)
Many people are lured into purchasing Burning Bush because of its beautiful red fall color but don't be one of them. This shrub will easily reach five feet tall and wide, many times growing larger, and used as a fall specimen plant or a hedge. This invasive shrub has been reseeding in filtered shaded areas and full sun throughout Pennsylvania. Given half a chance, it will shade the herbaceous layer in our forests, causing a monoculture within wooded areas. It is native from Northeastern Asia to central China. A good substitute for Burning Bush is Smooth Sumac, Rhus glabra. This native plant gets a beautiful red fall color and adds additional interest with its red fruit. The industry has been cultivating Smooth Sumac, making selections that are stunning. It is becoming more available in the nurseries, and garden centers in our area.
As we become more familiar with the invasives, we can make educated decisions about what plants we choose to plant in our own gardens and landscapes. As you see from the few listed here, invasive plants are not just weeds. Often, they are shrubs and trees that we have been planting for years. Consistently urging the plant industry to sell the plants that we want will encourage new selections and varieties of our native plants. Ask your garden center or nursery for native and non-invasive plants.
Check out Pennsylvania DCNR for other invasive plant species.
Mary Ann Ryan is the Consumer Horticulture Educator for Penn State Extension in Adams County. Penn State Extension of Adams County is located at 670 Old Harrisburg Road, Suite 204, Gettysburg, phone 717-334-6271.
Monday Videos: Visit us on Facebook at Penn State Master Gardeners in Adams County for our Master Gardeners' Monday Videos. Timely and relevant topics will be discussed on a weekly basis keeping readers up to date on current horticultural issues.
Hotline: The Master Gardener Hotline is open April through September on Mondays, Wednesdays, and Fridays from 10 am to 2 pm. Please send an email with pictures to adamsmg@psu.edu with your gardening questions or call the Extension Office at 717-334-6271 and a Master Gardener will contact you.
