Exotic Invasive Species

After returning to my office from summer break, this critter was sitting on my desk. My first concern, after a bit of panic, was who put this here, and more importantly, where did it come from. Turns out Jim, our forestry instructor left it there. It is the Asian Long-horned Beetle, Anoplophora glabripennis. This beetle is a wood borer, feeding on many types of trees, most frequently on Maples.

In discussing this with Jim, I can verify that this beetle IS now in Ohio. The specimen is from Clermont County outside of Cincinnati. Quarantine efforts are under way to try and control this species. Several other states have been able to do so, and even eliminate it completely. Lets keep our fingers crossed.

The Common or Purple Teasel, Dipsacus fullonum (or sylvestris), is a plant introduced to North America many many years ago. It has been here so long many people consider it naturalized. Labeling an introduced species as "naturalized" is a debate I don't wish to discuss. Teasel has an interesting blooming habit. The first flowers appear in a circular row in the center of the flower head. The top and bottom fill in later. The long sharp bracts you see on the sides were once used as a tool for separating cotton fibers.

Another relative is the Cut-leaved Teasel, Dipsacus laciniatus. I call it the White Teasel. A decade ago I used to see it only in central Ohio. Each year I've watched it travel county by county down Rt. 33, and now it has arrived in Athens County. In fact I now find it throughout the state.

White Teasel is taller and a bit more stiff or erect, and the leaves are more divided than Common Teasel. Teasels grow in disturbed sites and commonly along roads. Mowing highway edges is said to have increased the spread. Burning and herbicide will kill it.

Japanese Barberry Berberis thunbergii, was introduced as an ornamental plant. Its growth form is similar to our native barberry species. It forms dense hedgerows. It simply became easier to propagate than our natives. It is recognized by the small spoon shaped leaves. They are alternate in arrangement, but grow in a cluster that often appears whorled.

The red barrel shaped fruit hang down on a stem, and grow in long rows. The twigs are not round but angled. The twigs are also covered in thorns or spines.

Another identification method is to take a knife and scrape off the bark. The inner twigs are a bright yellow in color. Competing for space with natives is of course the problem with all exotic invasives, but Japanese Barberry also alters the nutrient content and pH of the soil.

There are two Buckthorns invasive in Ohio. This is the Common Buckthorn Rhamnus cathartica. I usually find it growing like a shrub, but it can attain a large size. The leaves are egg shaped, somewhat dull on the surface, and with a finely serrated margin. With age some twigs may show thorns. Like Barberry, look for a yellow sapwood inside.

The other species is European or Glossy Buckthorn, Rhamnus frangula. It is sometimes called Alder Buckthorn, but since there is a native species with that name, I don't use it. The name glossy refers to the leaves, which are much shinier than the previous species. The margins are entire or wavy. Leaves of Buckthorns have deeply impressed veins.

Buckthorns produce red to black berries that are now eaten by birds, contributing to their spread. Like other species, they were originally used as ornamentals.

Buds on Common Buckthorn appear somewhat scaled. On Glossy, the buds are naked. In other words soft, brown, and fuzzy, similar to a Pawpaw bud. This species is common along abandoned railroads and nowadays on bike paths. I don't know the full extent of Buckthorn spreading in Ohio, but I see cathartica more often in northern Ohio, and frangula in southern portions of the state.

Japanese Knotweed is actually a type of Smartweed. Known as Polygonum cuspidatum or sometimes Fallopia japonica, it is commonly planted along highway hillsides. It is technically a herbaceous wildflower, but grows in large dense thickets like a woody shrub. This is due to the underground rhizomes. They dominate the soil and for this reason have been used in erosion control.

Japanese Knotweed has large broad leaves, pointed at the tips, but squared off or flat at the bases, similar to a Cottonwood leaf. The margins are entire. Because of the tough roots, it takes multiple applications of herbicide to control it. Not into chemicals? To get rid of it, pull it up and eat it! It's high in vitamin C.

Many countries that deal in economic trade with the United States do not use plastic peanuts or styrofoam to ship goods. Instead they pack with natural materials known as excelsior. Excelsior is made up of wood, bark, and leaves. This is a major way exotic insects and plants end up in our country. It is believed that is how the above species entered our environment. This is Japanese Stiltgrass, Microstegium vimineum.

Stiltgrass can be recognized by the bamboo like leaves. The center vein is usually white or silver. Besides seeds, it has vegetative reproduction, and can form solid mats along the ground.

It is best controlled by herbicide. If you wish to pull it out by hand, wait till late summer or fall, the end of the growing season. Mechanical control in early summer only stimulates it to grow back.

I have posted on the Bush Honeysuckles, and now these. There are SO many exotic invasive species, I expect to do more on this topic in the future.