Don’t worry, I haven’t gone off the deep end wearing a tin foil hat. And I’m not talking about little green men from Mars in flying saucers. I am, however, using the word in its literal sense. What I’m referring to is all of the non-native and invasive plant species we find in William B. Umstead State Park that I have a lot of experience with and, collectively, we spend a lot of work hours trying to get rid of. According to the dictionary, the word alien means “belonging to another country or nation”. There are a lot of problematic invasive plant species that plague our park, but I’ll just touch on three specifically that give us the most trouble.
The first plant that we do battle with on a weekly, if not daily basis, is Autumn Olive or Elaeagnus umbellata. First imported from Asia in the mid 1800’s for erosion control, Autumn Olive is a bush-like plant that can grow as tall as twenty feet and produce thousands (yes…I said thousands) of little berries that are adored by birds and wildlife. The troublesome weed does just fine in poor soils and does well in shade or sun, so pretty much everywhere in the park. We tend to find it forming dense thickets in valleys along Ebenezer Church Road on the eastern border of the park and along our powerlines where birds like to sit and deposit the seeds mixed with a little of their own … semi-liquid fertilizer.
What’s so bad about this plant? Well like many invasive species, Autumn Olive can be so aggressive that it can outcompete other native species and create somewhat of a monoculture. That means that the hornbeams and oaks don’t get enough sunlight to grow on the forest floor because the sun is being blocked out by the dense foliage of all that Autumn Olive. This plant is pretty identifiable by the (what I call) “Tin-Man Silver” on the underside of the leaves.
And when the plant fruits around July, you can see it dripping with small red olive-like berries that are actually edible by humans. While the unripe berries are highly astringent, ripe berries can be rather sweet and palatable. So palatable, researchers at Cornell University and the University of Wisconsin looked into the possibility of growing autumn olive as a commercial crop due to its ability to thrive without the use of pesticides and herbicides and its high levels of lycopene. Luckily, they decided against it for fear of it escaping onto neighboring farms.
The next on our list of bothersome aliens is Chinese Wisteria. You probably just saw this plants flower blooming recently as it hangs off vines in many residential areas. The purple cluster of flowers smell especially good and can provide privacy between properties. Many people plant this in their yards and do a pretty decent job of keeping it at bay with proper trimming, cutting, and the possible use of herbicides. The problem occurs when someone plants Chinese Wisteria and, for one reason or another, the plant isn’t managed properly.
That happened when folks moved out of the properties that now make up William B. Umstead State Park in the 1930’s and left their Chinese Wisteria plants to grow unchecked. The spreading vines crawled along underneath the accumulating leaf litter and sprung up twenty feet away in each direction.
Then the vines crawled up tall trees, tightly winding around and choking the life out of their timber-based ladder as they grew, and then dropped their seeds to exacerbate the problem. Once Chinese Wisteria gets a foothold in an area, it can be a decades-long effort to try and eradicate the plant from that location.
The final plant I’ll bring up is one we find specifically in the floodplain areas of our park that possess sandy and wet soils. Chinese Privet, with its blue and black berries that are a favorite of many songbirds, infests many of our low-lying areas in the park. Most people won’t notice it because it thrives in hard to reach areas of the park, but where it is found it can be abundant. We tend to find it near the confluence of Sycamore and Crabtree Creek, along Richland Creek, and the headwaters of Sycamore Creek north of Big Lake.
What is actually kind of refreshing about Chinese Privet is that when the plant is young, it can be removed without the use of herbicides. Its naturally shallow roots combined with the sandy soil it thrives in allow it to be pulled quite easily from the ground.
This makes the effort of removing the plants a lot more family friendly, and we’ve hosted a number of volunteer events where children have helped remove privet from the park. However, left to mature, Chinese Privet can grow to look like any other small tree in the understory and send up new growth from lateral roots that require the use of herbicides.
So, what can you do to help mitigate the problem of invasive “aliens”? Well to start, if you’re a homeowner, please don’t plant these plants on your property. If you have these or any other invasive species on your property, safely remove them and replace them with a native plant. Instead of Wisteria, plant Purple Passionflower. You’ll love its purple flowers that grow into a temperate climate passionfruit that is reminiscent of the tropical varieties or better yet, the native wisteria. Instead of autumn olive, pick something useful and edible like highbush blueberries.
And the second thing you can do is volunteer to help remove the species we have at our park. Every year we hire seasonal park attendants who spend at least thirty hours a week doing nothing but mitigating invasive species, and that’s on top of the numerous hours a week that our ranger staff also commits to this endeavor.
If you’re curious about whether or not you have invasive species on your property, and good native plants to replace them with, check out these resources from NC Agricultural Extension. With any luck, and a lot of hard work, we’ll be able to avoid a full scale invasion of these “aliens” in our beautiful park.
- Ranger Nick Dioguardi
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