Garlic Mustard is a biennial of the mustard family that can grow to of height of 1-3 feet. Leaves give off a garlic odor when crushed. Rounded leaves with teeth grows in low rosettes in the fall of its first year, remain green over the winter, and resume growth the following spring. Flowers are white, each with four petals resembling a cross. Each plant can produce an average of 800 elongated pods, also called siliques, encasing seeds which becomes shiny and black when mature.
Garlic mustard was introduced from Europe in the 1860's to be used as food and medicinal purposes. Today it is found from eastern Canada, south to Virginia and as far west as Kansas and Nebraska. It is mainly found at forest edge and roadsides, but can tolerate heavy shade and may be found in floodplains. Though invasive in a wide range of soil and light conditions, garlic mustard does not tolerate areas of high acidity.
Garlic mustard develops rapidly in the spring of its second year, produces its seeds, then dies in late June of the same year. Long distance dispersal of seeds are either by humans or animals, as the seeds are too heavy for the wind to carry and do not float well in water. Because native animals do not like these exotic plants, they reduce the competition by eating native plants.
As with most exotic plants, garlic mustard also out-competes native plants for nutrients, water, light, and space. Many wildlife species that depend on the native wildflowers that complete their life cycles in the springtime are deprived of the essential food sources.