Invasive plant species are described as plants not native to a specific area that have no natural predators and overcompete for resources, endangering native plants and upsetting the delicate balance of an environment's ecology.
An extensive list of invasive species can be found on the ecology site BC Invasives. Many plants, such as foxglove or canada thistle, have become so populated that they are often mistaken for indigenous plants, but crowd out foraging grasses, crops, and upset the balance of our natural habitats. Many invasive species were brought over for decoration, but have escaped to terrorize local vegetation. Therefore it is important that, when curating your garden or green space, you are taking into account a plant's origins and growth habits. Of course, it is always better to plant native wildflowers, grasses and trees whenever you can!