There’s nothing more frustrating for gardeners than discovering that their well-planned plots or rolling lawns have been infiltrated by invasive plant species, the perennial marauders of the back yard set. While many people panic and immediately start yanking or mowing the intruders when they first make their appearance, a gardening expert advises that it’s best to investigate the plant that’s choking your columbines or blighting your lawn before complicating the problem with an errant course of action.