Invasion

© Dave Spier

There's a wildflower that's trying to take over much of the country from Alaska to Georgia and all of the northeast to Quebec. (The USDA has a range map on their website.) It tolerates shade and crowds out native plants. Deer are repulsed by its garlic odor and flavor, making it a clever defense in hindsight. It's a prolific seed producer and if that's not enough, it releases chemicals that inhibit the growth of other nearby plants, particularly native tree seedlings. We're talking about Garlic Mustard (Alliaria petiolata, = A. officinalis and two other synonyms), a true member of the mustard family and relative of such familiars as cabbage, broccoli, cauliflower and of course, other mustards including the one used in the condiment.

Garlic mustard is a biennial. It takes two years to fully mature and go to seed. The first year, it produces only a few rounded to heart-shaped leaves as it concentrates on growing a root system. The second year, new and larger leaves (more triangular and coarsely toothed around the edges) emerge. A stem averaging one to two feet high sprouts a cluster of small, white flowers, each with four petals. These produce long, thin seed tubes that eventually dry, split and release two rows of numerous black seeds to start the process over again.

This invasive weed was brought here from Europe and Asia in the 1860's, probably to be used as a potherb. Various recipes can be found on the internet and involve using young leaves and flowerbuds and to a lesser extent flowers and seeds. This is another case of "eat it, if you can't beat it." From the looks of it, there are far more plants than we could possibly eat, so the next alternative is to pull them up by their roots, put them in a black plastic bag in the sun and eventually bury them in a long-term compost pile or otherwise dispose of the plants depending on the regulations in your neighborhood. Don't let them lay around. Even if you dry the roots and let the plant die, the seeds continue to mature. Mowing does nothing to stop the invasion because the roots quickly grow new stems and leaves and then flowers at a lower height. The seeds can lie dormant up to five years and then sprout, so the best alternative may be to trash the seed heads.

In its native Europe and eastward to India and western China, 68 insect species and seven types of fungi feed on the garlic mustard. None of these controls are present in this country. To make matters worse, deer eat our native wildflowers instead, making more room for the garlic mustard to flourish.

In Defense of Plants sent me information on a book called Garlic Mustard - from Pest to Pesto. If you have any suggestions for controlling garlic mustard, or recipes to share, please send them along with any corrections, comments and questions to northeastnaturalist@yahoo.com or connect through my Facebook page and photo page. There's also a community-type page for The Northeast Naturalist. Other nature and geology topics can be found on the parallel blogs Adirondack Naturalist and Heading Out.