What are Invasive Species?

On Monday Bea Corra from Parkersburg shared a picture of a plant on our Facebook page wanting to know what type of plant it was and whether it was invasive or harmful.  I instantly had a flashback to August 2005 when I was studying Plant Taxonomy at Marshall University.  The plant (right) is Japanese Knotweed, an invasive species.  I also remember Dr. Evans’s advice for getting rid of it … “sell your house”.  This week, we’re going to take a look at what makes a plant invasive and some of the most common in our region.

Invasive plants are plant species that are not native to a specific location and has a tendency to spread.  These plants are able to outpace native species, damage the environment, and have economic impacts.  Many invasive species were actually introduced as ornamental plants or for agricultural purposes.  Kudzu, one of the most vilified invasive species in the US, was featured at the Philadelphia Continental Exposition in 1876 as an ornamental vine, shade producer, and a way for farmers to control erosion.  As the writer James Owen said, “Don't ascribe to evil what can be attributed to well-intentioned stupidity.”

Japanese Knotweed, fallopian japonica, is a good example of an invasive species that was introduced as an ornamental plant.  The weed can now be found in 39 of the 50 states, and it is listed as one of the world’s worst invasive species.  Its root system and strong growth can damage concrete foundations, buildings, roads, and retaining walls.  It can also reduce the capacity of streams to handle floodwaters by clogging the banks with thick growth.

It might smell nice, but Japanese honeysuckle is another invasive species.  Its ability to endure our cold winters means that it can keep growing while native plants are dormant.  The Chinese word for the plant literally translates as “winter enduring vine”.

A plant many gardeners fear is Johnson grass, sorghum halepense.  Get this stuff in your garden, and it is nearly impossible to eliminate.  It is named after an Alabama plantation owner, Colonel William Johnson, who sowed its seed around 1840 as a perspective forage crop for cattle.  It grows and spreads so quickly, it an choke out other crops planted by farmers.

Some invasive species are so commonplace in our area, they might seem like a natural part of the landscape.  Blue bugle, ajuga reptans, is a plant that we see covering entire yards and field with little purple/blue blooms each spring.  It was introduced from Europe all the way back in colonial times.

I could write a much, much, much longer post, but I just wanted to highlight a few species in our area with interesting stories.  Check out this list on Wikipedia of invasive species in West Virginia.  If you are interested in native plants, check out the West Virginia Native Plant Society.