Invasive Invade! To the untrained eye, the Don Valley appears to be filled with lush vegetation. Along the trails and at restoration sites, there is an abundance of greenery. Sadly, much of that vegetation is made up of a few aggressive species that are slowly taking over large areas. These plants are invasive species. Throughout the growing season, volunteers and City staff spend countless hours cutting and applying specific chemicals directly to these plants, from Creeping White Clover to towering Norway Maples, in an attempt to stop invasives from taking over the valley entirely.