Invasive Plants - Why Are They Here and How Can I Help

An invasive plant is generally a non-native plant that is able to aggressively spread and thrive in areas outside of their natural habitat.  Many of them share the characteristics of growing quickly, reproducing fast and easily adapting to new environments.

People often innocently plant invasive plants because they're looking for something unique.  When out hiking, seeds can stick to the bottom of shoes and be moved to other areas.  Pet stores may have animals from other countries that could unknowingly be carrying seeds.  Seeds can stick to any kind of vehicle and be spread around.  Weeds can be stuck to firewood.  Invasive plant seeds can be mixed with other seeds that you purchase.

There are a lot of reasons invasive plants spread so quickly.  If they've been brought into a new environment they may not have any natural enemies such as insects, diseases or animals to control them.  With their aggressive growth they can quickly take over space, light, water and food that native plants need.  Large wildfires can sterilize the soil and wipe out the existing plants.  These areas often produce ideal conditions for invasive plants to take over.

Invasive plants aren't always species that have been introduced to non-native areas.  People making changes to habitats or even excessive rain or lack of rain can cause native species to become invasive.  Even in gardens, if perfect conditions are available ordinary garden plants can invade large areas.  A few that come to mind are mint and artemisia.

Damage from invasive plants is over $100 million a year in the United States alone.  They choke out native plants and cause losses in agriculture and farming.  They can result in economic losses from tourism by impacting fishing, hunting, hiking, wildlife viewing and water sports.  They also increase the chances of exotic diseases by creating new environments in which unwelcome pests can thrive.  Examples of some of these diseases are West Nile virus and malaria.  The pesticides used to try to get rid of these pests can then end up polluting surface water and soil.

So what can we do to prevent the spread of these plants?

-Make sure the plants you purchase and use aren't considered invasive in your area. 

-Clean your shoes if you've been in an area that could have contained seeds of invasive plants.

-Clean your boat when moving it to another body of water.

-Replace invasive plants in your yard with non-invasive species.

-If you see invasive plants, remove them.  They often thrive in sidewalk cracks, abandoned parking lots and gutters.

By remaining aware of invasive plants in our area, we can make a difference in protecting our native plants and reducing the spread of these pest plants.

To view of a list of invasive weeds by state, go to Invasive Weeds by State or to view a list of invasive species in many other countries visit Invasive Species by Country.

 Reference: 

The United States National Arboretum

All photos in this article came from Wikimedia Commons. Please scroll over each photo for plant identification.