Controlling Invasive Plants the Easy Way
- Cathy Rees
- 9 minutes ago
- 3 min read
We are seeing a proliferation of invasive plants along the roadsides and also much closer to home—in our own gardens! While I’m not sure how close the nearest invasive honeysuckle, bittersweet, barberry or multiflora rose is to my house, I can tell you that my garden and woodland are not immune from seedlings sprouting up at this time of year. This is a great time to go out on patrol. To do that, you need to arm yourself with photos of what these plants look like when only a few inches tall, and you also need to know where to look. The great thing about doing this now is that you can easily remove each seedling with your bare hands. No saws, shovels or pruners needed! And it is so satisfying to know that you just arrested a much larger problem in the making!
Let’s start with the seedlings. Barberry (usually Berberis thunbergii but sometimes Berberis vulgaris) is easy to spot by its round leaves and very thread-like petioles that attach the leaves to the stem. Of course, you should familiarize yourself with the mature plant as the seedlings will have a resemblance. Also, remember that the cotyledons—those are the first leaf-like structures the seed puts out before the true leaves emerge—are not indicative of the true leaf shape. Another sign of a barberry seedling is the yellow root. If you were to dig up a mature plant you would see that the interior of the much larger roots are bright yellow, as well.
The non-native, invasive honeysuckle seedlings (usually Lonicera morowii) likewise bear a resemblance to their mature relatives. The leaves are arranged in pairs along the stem, each leaf opposite another. They are roughly oblong, but what distinguishes them from many other plants is that the leaves of L. morowii are almost downy on the lower surface. If you see a seedling with a woody stem, opposite leaves that are not toothed or otherwise divided and they have short hairs on the underside, you likely have this invasive honeysuckle.
Another plant we are seeing by the hundreds is bittersweet (Celastrus orbiculatus). This twining vine grows upright as a seedling and doesn’t yet reveal a long tendril at the tip. Its leaves are shiny and slightly toothed as they come to a point. The root is almost orange. It is typically a light green, but if the plant is stressed, it will turn bright yellow as it does in the fall, which is also a helpful signal for identification.
Multiflora rose (Rosa multiflora) is also becoming common in our area along roadsides and woodland edges. The leaves are divided like the rest of the roses but even the seedlings show the distinctive bract at the base of the leaf which looks almost like hairs where the leaf attaches to the stem. On other roses, the bracts are solid and look somewhat like an ear.
The seeds of invasive shrubs are spread by birds that eat the fruit and eliminate the seeds after the fruit has been digested. This is likely to happen where you see birds perched in your yard, especially around trees and shrubs near the bird feeder. Also, check below trees and shrubs with dense foliage for cover. If you see one seedling, look around carefully for more, because there is usually more than one seed in a single fruit and birds will consume a lot of fruit at one time. Check in places with bare soil. Often seedlings get started in places where there is little competition for moisture and light.
However, do not ignore lawn areas or garden areas where there is plenty of existing foliage. A neighbor found thousands of bittersweet seedlings growing in the grass below her crabapple tree. She was able to pull many of these and, in this case, do some mowing to remove the leaves and prevent them from photosynthesizing. When just a seedling, the plant has few resources saved up in its meager roots to sprout a whole new set of leaves.
Native Gardens of Blue Hill is offering a workshop on removing fully mature invasive plants on Tuesday August 5. Visit our Upcoming Events page for more information and to sign up.
