This is the perfect time of year to tackle our first invasive foe of the season: Garlic Mustard (Alliaria petiolata). If you’re gazing out the window along the Transitway or parkways, you can’t miss this white-flowered plant standing out from the grass or other herbaceous plants around it. Rarely does one plant grow alone, so also noteworthy is its nature of having one tall plant in the middle surrounded by many of its smaller brethren (or children!) This group growth form is due to the way Garlic Mustard produces many seeds, which it then releases in the same location.
Garlic Mustard is a shade-tolerant biennial plant that thrives in woodland settings. It is considered a serious invasive pest of natural areas, particularly woodlands, displacing native flora and severely reducing species diversity. Its aggressive, rapid growth allows it to form dense carpets that prohibit growth of other species.
Recent research shows that Garlic Mustard can release chemicals that destroy the mycorrhizal fungi that many trees depend on for nutrients. This allelopathy means that when Garlic Mustard invades a site, growth of tree seedlings is reduced. Maple trees are particularly susceptible. Like many non-native plants, Garlic Mustard has few natural enemies to help keep it in check.