One example of an invasive plant species is a Japanese vine called Kudzu. This plant is non-native (Exotic pest plant, invasive exotic). A number of organizations have implemented plans to deal with these invasive plants, as they cause a great deal of damage to the environment.
Noxious weeds can be very dangerous to grazing livestock, cows, for example. Leafy Spurge is one example of a noxious plant that can be harmful to wildlife.