PLANT INVADERS

What are invasive species?

Invasive species are plants or animals that

have been transported by humans from distant lands,
escaped cultivation,
spread rapidly in the absence of the natural controls (e.g., herbivores, parasites, and diseases) that exist in the area from which they came, causing harm to native plants and the local ecosystem.

Invasive species prosper in disturbed areas. Relative to native plants, invasives grow quickly, begin reproducing early in their lifespan, produce abundant seeds, and spread rampantly often using runners or tubers in addition to seed propagation.

Note, however, that many non-native plants are non-invasive; for example, plants grown in vegetable gardens.

How did invasives get here?

Some introductions were accidental. Japanese stiltgrass was inadvertently introduced through its use as a packing material.

More commonly, they have been sent, carried, or planted anew for a variety of reasons.

Immigration. European settlers to North America brought the common dandelion with them to plant for food and medicinal use.
Exploration and Discovery. Explorers Lewis & Clark were directed to bring back specimens from their travels. One of these is Oregon grape (mahonia) which has become invasive in Virginia.
Ornamentals. At the turn of the last century as gardening became more popular, some of the most damaging invasive species were introduced to North America including privet, Chinese wisteria, English ivy, and porcelain berry.
Erosion control. The U.S. Soil Conservation Service planted a million acres of kudzu in the 1930s and 1940s to mitigate erosion.

Why you should care!

Invasive plants covering the ground and trees

Invasive species threaten and crowd out the diverse set of plants and animals that have made up the diverse ecosystem in our area for tens of thousands of years.

Lacking the natural controls that existed in the area where they originated, invasive plants spread rapidly, crowding out and killing native plants. Invasives often grow so densely they smother other vegetation, replacing species biodiversity with a monoculture (a single invasive species dominating an area).

A consequence is decreasing populations of insects, birds and other wildlife that depend on native plants for food. Invasive species are of much lower food value to animals and the leaves or fruit of some invasives is toxic.

What you can do!

Don’t plant invasive species.
Remove invasive species on your property. Tips and advice on best resources for learning more about removal are included for the Worst 10 invasives.
Plant native species. We provide advice on the best resources for choosing native plants on our “Help save pollinators and birds” page (forthcoming).
If you wish to plant a non-native plant, make certain it is not invasive.