Invaded by non-native plants which seem to, not only survive, but thrive in our area. The problem? In many cases they take over and overwhelm native plants which then die out.
But you say, we still have these interesting plants in their place. Indeed, but the loss of native plants affects more than the individual plant. For example, some plants are the favorite (or virtually only food) for some of our native caterpillars. No food = no caterpillars. The problem? no caterpillars = no butterflies - an obvious loss of beauty in our gardens.
Local nurseries and garden centers are still selling these "pest" plants to unsuspecting home owners. Once planted many of these plants are almost impossible to get rid off. So knowing about some of the more common ones, will help you avoid inadvertently bringing home a "pest plant". There are links below which will help.
Some invasive plants are native, but equally vigorous in their spreading habits - bad enough in one's yard, but particularly troublesome if they are allowed to creep and leap into parks and woodlands.
I made the mistake of planting a Trumpet Vine to attract hummingbirds....and it does that... BUT it also wants to vigorously spread everywhere. Little Trumpet Vines come up everywhere, including cracks in my flagstone patio.
Be thankful if you've never had to battle bamboo! A neighbor planted some long ago, and we still battle the nasty stuff. It has now invaded Rock Creek Park behind my house. It is almost impossible to kill and sadly, deer do not eat it!
A number of local organizations have developed to try and stem the tide of these invaders. Some sponsor "clean-up" days when they try to pull out the non-natives from areas in our local parks. Some local citizens groups have participated in the effort.
Here's some links to local groups and information about local invasive plants: