Saturday, May 8, 2010

Chicago River Day 2010

Saturday, May 8, was the annual Chicago River Day, sponsored by Friends of the Chicago River. Since the Skokie Lagoons are part of the Chicago River system - they are impoundments of the east fork of the North Branch of the Chicago River - we were pleased to host a group of eager River Day volunteers in addition to our regular crew.

It is springtime at the Lagoons, and that means it's time to pull garlic mustard as it sprouts. Garlic mustard (Alliaria sp.) is a small herbaceous plant native to Eurasia. As European settlers arrived in North America, they brought with them a variety of familiar plants from their old homelands. Garlic mustard can be eaten in salads or used as a cooking herb. As the name suggests, it tastes like garlic. While it is tasty and features pretty white flowers in the sprintime, garlic mustard is an invasive plant - it spreads rapidly, especially in disturbed areas such as road and trail edges, and crowds out native plants. Like European buckthorn (Rhamnus cathartica), another Lagoons invader, garlic mustard creates a monoculture where it grows. That means that only one species - garlic mustard - grows in a particular area. A healthy woodland will have a wide diversity of plant species on the forest floor. While the monoculture forest floor will look green, it is not a healthy community. Few, if any, native North American species will eat garlic mustard.

However, like buckthorn, garlic mustard can be controlled and removed through focused stewardship efforts. The key is to pull it in the spring, before it goes to seed. Garlic mustard is easily identified based upon its tall shoots, distinctive serrated leaves, small white flowers, and garlicky odor when the leaves are crushed.

On River Day, we pulled enough garlic mustard to fill fifteen large garbage bags! The aftermath is shown at left. We'll continue to monitor the area for resprouts so the restored section will remain clear of garlic mustard.