Garlic mustard is a biennial herbaceous plant with triangular, coarsely toothed leaves that give off an odor of garlic when crushed. First-year plants appear as a rosette of green leaves close to the ground, which remain green through the winter and develop into mature flowering plants the following spring. Plants reach up to 3½ feet in height and produce clusters of small white flowers, each with four petals in the shape of a cross, from May through June.
Native to Europe, garlic mustard was introduced into the northeastern U. S. in the 1800s for food, erosion control, and medicine. Today it frequently occurs in the moist, shaded soil of river floodplains, forests, roadsides, trail edges, and forest edges and openings. Seeds are produced in erect, slender pods that become shiny black when mature. A single plant can scatter thousands of seeds over several meters.
Garlic mustard out-competes native wildflowers and deprives wildlife of a food source. Due to the seeds remaining viable in the soil for five years or more, effective management requires a long-term commitment. Hand removal is possible for light infestations, but care should be taken to remove the entire root system. For very heavy infestations, application of a systemic herbicide is effective.