Q: Interested in learning more about what plants are invasive and why that matters?
A: Head on over to Invasive Plants by the United States National Arboretum for all the information you’ll need. Scroll down that page for a link to your state where you can find out more about invasive plants that are causing problems in your locale.
For Pennsylvania the DCNR lists many forbs/grasses as invasive.
For a plant to be invasive