Two Troublesome Groundcovers
by Sally Elmiger
Some groundcovers in our landscape are so common that we practically dont even notice them. Who doesnt have a bit of myrtle or English ivy in their yards? They make a great mat under a tree or in a shady spot many other things wont thrive in. These qualities make these two trouble for our natural areas.
This low-growing plant is a native of Europe and has been grown in this country horticulturally for centuries. It has shiny, oblong, evergreen leaves that grow opposite one another on a trailing stem. In the spring, small lilac flowers appear whose petals are squared off at the ends. These flowers can reappear sporadically throughout the growing season. Vinca does best in shady areas in rich, moist soils, but will live and spread less rapidly under most soil conditions.
This plant does not spread by seed, but spreads vegetatively. As the stems grow across the ground, roots are formed at nodes along the stems, allowing the plant to colonize new areas. Myrtle forms a dense mat that will expand indefinitely from its parent, crowding out other low-growing native plants. If planted near a wooded area, vinca will invade the woodland and eventually take over the ground layer if left unchecked. Large areas of myrtle can be seen in the woodlands in northern Ann Arbor along Huron River Drive (west of Main St.), or at Hidden Lake Gardens, located just west of Tipton, Michigan.
To control or eradicate myrtle, pull up the plants and rooted stems. Once the runners are removed, you can also mow the plant. Since all parts of the stem can potentially become a new plant, be sure to remove all the stems. Myrtle is most vulnerable in the spring, when it is putting all its energies into growing and flowering. At this time, you can cut the plants off and apply a glyphosate herbicide. If any new plants emerge after this treatment, dig them up or spot-treat with the herbicide.
Another low-growing, evergreen plant, English ivy can grow either as a groundcover or a vine on woody stems reaching up to 90 feet in length. As the name suggests, it is not from North America, but from Eurasia. It has been cultivated in this country since colonial times and is a serious threat to our woodlands, particularly in the northwest and California.
English ivy leaves look similar to a maple leaf, with three to five lobes. On mature plants (about 10 years old), leaves have an egg shape. It also produces flowers in the fall at the tips of the stems, and blue fruits that are eaten by non-native birds such as starlings. Otherwise, it is not used by native wildlife.
Like myrtle, this ivy blankets an area once it is established and tolerates the densest of shade. It crowds out all other vegetation, perennials, shrubs, and trees, and can grow up a large tree, adding weight that could increase the possibility of storm damage.
This plant spreads by seed, but cut stems in contact with moist soil can also root. To remove English ivy, cut the runners from the plants and pull them down. Then dig up the plant. Unfortunately, herbicides are ineffective, as the leaves have a thick waxy protective coating.
What to Plant in Their Place?
One way to lessen the threat of invasive plants is to make sure there is a lot of competition for resources. Planting natives once youve removed the invasive plant is a positive control method that makes it tougher for the invasive plant to recolonize an area.
Here are some suggested native groundcovers and vines to try in shady areas. Remember, however, that the look the native groundcovers provide can be much softer, and most likely will not be like the dense monoculture the troublesome plants create.
Details about all of these native plants can be found in the natural landscaping brochures produced by Ann Arbors Natural Area Preservation Division. For copies of this four-brochure series, call 734-996-3266.
Randall, John M. and Janet Marinelli, Eds. Invasive Plants: Weeds of the Global Garden. New York. Brooklyn Botanic Garden. Winter, 1996.
Dirr, Michael A. Manual of Woody Landscape Plants. Illinois. Stipes Publishing Company. 1990.
Article reprinted from the Summer 2000 issue of the Ann Arbor Wild
Ones Newsletter. Copyright © 2000 Wild OnesNatural Landscapers,
For more information...
...and photos from the University of Connecticut Plant Database, see the following: