Beware invaders

Watch out for these plants when cleaning your gardens

Watch out for these plants when cleaning your gardens

November 05, 2006|by JULIE E. GREENE

For years people have heard Africanized honeybees are moving north and, more recently, that armadillos are expanding their territory north.

While neither has apparently made it to the Tri-State area yet, they could one day.

What is already in Washington County and probably in nearby counties are several invasive plant species that can quickly overgrow native species, changing the local ecosystem, says Kerrie Kyde, habitat ecologist and invasive plant specialist with the Maryland Department of Natural Resources (DNR).

Some of these plants are attractive, so people who find them in their backyard might leave them because they tend to grow easily. However, they can threaten some native plant and animal species by changing the ecosystem, experts say.

As residents take time to clean their yards and gardens this fall, they should keep an eye out for these invasive species. If it's safe, pull them out and throw them in the trash - not the yard waste because their seeds might survive the composting process, Kyde says.


Others might need more care in removing because of harmful health effects, officials say.

Here are some invasive plants local residents should discard if found:

Japanese hops - Phil Pannill, forester with the Maryland Forest Service in Hagerstown, recently received a grant to focus on controlling the spread of hops in the Monocacy watershed. Hops has nasty prickers on it that might irritate the skin, Kyde says. The vine, which sprawls and climbs, is often found along the C&O towpath and could be found in backyards that are near a creek, stream or flood plain.

Giant hogweed - This giant plant looks like carrot tops or Queen Anne's Lace on steroids, Kyde says. Do not try to remove hogweed, because the sap can make skin photosensitive, resulting in severe burns in sunshine. Call the Maryland Department of Agriculture's Plant Protection and Weed Management Office at 800-492-5590, ext. 5920. If you want to try to remove it yourself, wear long sleeves and gloves and cut it down with loppers or pruning shears. The stems, splotched with purple, can be an inch or greater in diameter. This plant reaches 10 feet tall when it matures and has an umbrella or flat-top cluster of white flowers. The enormous leaves resemble a rough-edged maple leaf shape. Prickers are on the stem and midrib of the leaves. While rare in the local area, giant hogweed is on the federal list of noxious weeds. It might be found in yards, along creeks and in flood plains and roadside ditches.

Purple loosestrife - This beautiful magenta perennial flowers in summer. It resembles a big candelabra with woody stems and long "candles" of bright magenta flowers in its top third (see photo on page E1). The dense root structure makes it difficult to remove. It is often seen in roadside ditches and gardens. A mature plant can reach 8 feet tall, though it would probably be about 4 feet tall in gardens. People can report sightings of this plant by filling out an online report at

Weed control personnel can remove the plant, or, if there is a large patch, release a galerucella beetle that eats purple loosestrife at all life stages.

Multiflora rose - This rose blooms along roadsides in May with a pretty, small white flower. It was once widely promoted and used by the U.S. Soil Conservation Service for hedges or fences to control soil erosion and fence-in livestock. The shrub rose can get 6 to 10 feet tall with big arching canes that form when plant tops fall over and root. The thorny rose also climbs trees. Can be found along roadsides.

Garlic mustard - This invader resembles a basil rosette with kidney-shaped, rough-edged leaves in its first year. These leaves resemble a violet's, but are thicker. In its second year, the stem produces a cluster of small white four-petaled blossoms at the top. It takes two years to become reproductively mature. Garlic mustard exudes a chemical from its roots that suppresses the germination of surrounding plants. A shade dweller, it is often found in the woods near creeks, but people are finding it in shady backyards.

Tree of heaven or ailanthus - This tall, gray-stemmed tree often grows with multiple stems in a small grove. It resembles a sumac or young walnut tree, but has smooth-edged leaves. These leaves turn yellow and drop quickly rather than turning red and orange like a sumac. Tree of heaven might be found in backyards, alleys, driveway cracks and roof gutters. Some people have experienced health problems, such as heart irregularities, when exposed to the sap and sawdust while cutting it down, Pannill says. Drivers along Interstates 70 and 68 might notice dead, standing stems that were ailanthus treated by state crews, Kyde says.

Bush honeysuckle - There are three species of bush honeysuckle, all of which can be difficult to distinguish from each other. The mature stem of a native shrub is solid, whereas the invasive stem is hollow, Kyde says.

Invasive animal species

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