Issue 6, May 28, 2010
Know Your Invasives: Garlic Mustard
One of the seemingly fastest moving invasive plants in Illinois is garlic mustard. In fact, in one Illinois study, it advanced an average of 20 feet per year, expanding as much as 120 feet per year. It aggressively invades forested areas and can be found along roadsides as well. It likes shaded areas, especially disturbed sites and open woodland. Garlic mustard can quickly overtake an area, excluding other herbaceous plants.
Garlic mustard is a biennial plant, with a two year life cycle. During the first year, it grows as a seedling and then a rosette stage plant, flowering in the subsequent year. These plants can grow 2-48 inches high. The basal rosettes have dark green, kidney shaped leaves. Leaves on the second year plant are more triangular and sharply toothed. They are one to three inches long and get smaller towards the top of the stem. In Illinois, flowers occur in May. Each flower has four white petals that narrow abruptly at the base. The plant will flower continuously at the top of the stalk. Individual plants will produce 350 to 7,900 seeds in narrow, linear capsules called siliques.
Garlic mustard can be distinguished from similar species by its characteristic garlic odor and 2-4 foot stalks with numerous white flowers.
Garlic mustard photo courtesy of Invasive.org