To pick just three invasives is hard. Unfortunately, we have a lot of established nonnative invasive plants in Virginia and several emerging threats on the horizon. Each person would likely pick different top contenders based on their experiences and eradication efforts.
All invasive plants have a few characteristics in common: they are aggressive growers, they reproduce quickly, there are few to no native species that consume them to help keep them in check and they are well-suited to flourish in the environment into which they are introduced.
All things considered, my top three invasives of the plant kingdom include garlic mustard, oriental bittersweet and Japanese hops.
Of the three, garlic mustard (Alliaria petiolata) actually has one desirable quality that the other two lack; it is edible and delicious! Many a fine quiche can be created utilizing the abundant greens in the spring when they are young and tender. As they grow and particularly after they flower, they tend to get a very strong flavor and become bitter. At some lower elevations, the greens are appearing now so get ready to gather the harvest. Garlic mustard can be used in everything from spaghetti sauce to stir fries to being eaten as a cooked green, Southern style, with a healthy amount of butter and a splash of red wine vinegar. It also freezes very well after being blanched, supplying some nice handy greens in the freezer for future consumption after all the outdoor plants have passed their prime.
For those not familiar with oriental bittersweet (Celastrus orbicalatus), in a word, it is horrible. Like kudzu and English ivy, bittersweet uses it vining growth to climb trees, engulf abandoned buildings and smother everything it covers, including our valuable native plants. Vines are particularly vexing as they can topple established trees if they grow long enough to reach the canopy, weigh the tree down and weaken its structure to the point where powerful summer storms and high winds combine to speed its demise.
The reddish orange colored roots are just scary, growing like a vast underground spider web. Begin pulling it by hand and it will come up with moderate effort, but it will disturb the soil for a far distance from the main vine.
Don’t be fooled by its attractive berries. Yes, they are nice for fall decorations but toss that attractive wreath out into the backyard once it’s passed its prime and a landscape management problem is born.
Take care with eradication with Oriental bittersweet: there is also a native bittersweet in Virginia which looks very similar – American bittersweet (Celastrus scandens). One way to tell them apart is that C. orbicaluatus bears blunt thorns and produces berries along the entire stem whereas C. scandens only has berries at the tips of the vines.
The final species which tops the do-not-plant list is Japanese hops (Humilus japonicus). This one particularly favors riparian areas and, like bittersweet, climbs over everything in its path. It blankets the banks of the Shenandoah and Rapidan Rivers, has taken hold along many a tributary and continues to colonize rich native habitats. It is of particular concern as floods help distribute the seeds farther downstream from the original site.
Japanese hops have a nasty defense to discourage its removal: tiny briars line its stems and pulling it by hand without gloves and long sleeves is akin to rubbing course sandpaper rapidly and repeatedly over one’s bare skin.
The seeds also have briars, a clever distribution technique, as they get caught in a passing opossum’s fur or hitchhike on the coats of raccoons, beavers and other rivers' edge inhabitant to be spread to other locations.
So, at this moment, these three nasties hold top places on my invasives list. It is a fluid list though and could easily change if I encounter a particularly large patch of Japanese stilt grass or wavy leaf basketgrass, porcelain berry, mile-a-minute weed or any of the other pernicious invaders. These and other plants are having a significant and lasting effect upon our local ecosystems. As always, the take away is plant natives!
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ORMN Class IX