Invasive vs. Aggressive

I often hear people refer to plants as "invasive" when I know they are just aggressive native plants. Invasive seems to have become synonymous with "weed" or generally any undesirable plant.

But invasive has a particular meaning that's very important. Invasive plants are not native. They have been brought into an area, usually by people, from somewhere else and have escaped into the wild to wreak havoc on the native plants. Most are very vigorous and have no natural competitors or predators outside their native range.

Some native plants are very vigorous, and changing conditions can make them a problem. An example is Virginia creeper. It's native to eastern and central North America, from southern Canada all the way down to Mexico. Clearly a Texas native, so not invasive. But it is very aggressive and has become out of balance in many areas. In a thickly forested areas, it doesn't get enough light to cause much trouble. But in backyards and the divided stands of trees humans leave around, it can easily overwhelm big trees. Still not invasive.

[Image: rescuegrass (mostly) - definitely invasive]

Rescuegrass, however, is not native to North America. It was brought in from South America for cattle forage and has overwhelmed a lot of land. Definitely invasive.

(Invasive does not just apply to plants; it also includes animals. But here I'm addressing the use of the word for plants.)

Then there are the naturalized or adapted plants. Not native but play nice with native plants. An example is blue mistflower. It is native further east but fits in well in Central Texas without threatening native plants. It's also good for pollinators, especially Queen butterflies, and it's beautiful. None in my yard, but I enjoy seeing it around town.