Above: Callery pear in autumn. Photo by Purdue University
It’s a sad but true fact – some historically favorite landscape plants have been proven to cause problems in woodlands and other natural areas as an invasive plant that limits the regeneration of native plants. In this article, I intend to give you food for serious thought regarding the consideration of replacing these plants with native plants.
Today, we’ll concentrate on three landscape plants that have been long-time favorites of homeowners and why they have been posing a problem in recent years. Some of the common offenders in home landscapes include Callery pear, Norway maple, and burning bush.
Callery pear, Pyrus calleryana, is a more generalized term we give to ornamental flowering pear trees, such as Bradford Pear, Cleveland Select Pear, Aristocrat Pear, and others. They are beautiful flowering trees in the spring and a popular past choice of homeowners to line driveways and use in other prominent locations. According to Purdue Extension’s Report Invasives website, https://ag.purdue.edu/reportinvasive/, “Callery pear may look pretty, but it’s crowding out Indiana native trees! It’s the first tree with white flowers in the spring and dark crimson leaves late into the fall. Its white flowers have five petals and a really unpleasant odor. Using Callery pear in your yard allows them to spread to forests and parks where it crowds out native plants. Some escaped trees are thorny which makes it difficult for wildlife and humans to move through the woods. The branches of these trees also frequently and easily split.”
Another long-time favorite of homeowners is the Norway maple, Acer platanoides, especially those cultivars that retain their deep red color all year long. This attribute has made Norway maple a popular choice because few other options exist that offer that color feature for the landscape. Report Invasives says that Norway maple out-competes many trees including the ecologically and economically important sugar maple. It forms a thick canopy that shades out the understory. Additionally, native trees like the sugar maple support many more native insects, which in turn feed native bird populations.
Finally, burning bush, Euonymus alatus, has been a favorite of many homeowners due to its fiery red color in the fall when the plant is in full sun. It’s a show-stopper! Like Callery pear, however, it similarly has become problematic in forests and other natural areas. The Report Invasives website summarizes why the plant is invasive, saying it is tolerant of full shade, can grow in dense thickets, and displace native plants. So, in forest situations it can grow in the shade under the tree overstory (canopy), and in late fall it will retain leaves past the time that most deciduous trees have lost their leaves. The leaf color will be a pale pink, rather than a fiery red, due to shading.
So, if these and other invasive plants are problematic, what should we replace them with? Purdue Extension has a free online publication entitled, Commercial Greenhouse and Nursery Production: Alternative Options for Invasive Landscape Plants, available at Purdue’s Education store, www.edustore.purdue.edu. Although the publication is primarily intended for commercial greenhouses and nurseries, homeowners can find native alternatives to Callery pear and Norway maple. Species listed include native species and non-native species that behave themselves.
Some possible native alternatives to burning bush could include black chokeberry, dogwood shrubs, winterberry, or others.
Other resources to consult are the Indiana Native Plant Society at https://indiananativeplants.org/ and the Midwest Invasive Plant Network at https://www.mipn.org/.
Now is a good time to do some research on your own as to what plants may work best for you as possible alternatives to invasive plants that linger in your landscape.