If you're not especially green-thumbed, chances are you don't give a second thought to what plants might be lurking at the bottom of your backyard. If you have invasive species hiding there, though, failure to do so could wreak havoc on your garden - and consciously owning them might even be illegal... An invasive plant is any type of plant that grows somewhere it shouldn't and in a way that's hard to control, and in the US, there are some common offenders that cause serious problems. Many of them grow incredibly quickly and can choke out surrounding native species, posing a serious risk to ecosystems. Since some of them can be quite decorative too, people mistakenly plant them or encourage their growth in their backyard.