We’re here to talk about our monthly Michigan invasive species, which is in full spring frenzy as we speak.
Name: Alliaria petiolata, commonly called garlic mustard.
Native Range: Europe
Description: Garlic mustard is an herbaceous plant (meaning it has no woody stems) that smells like garlic when you crush the leaves. The first year, it grows heart-shaped leaves in rosettes (circles, basically) close to the ground. The second year, the stem grows up from that rosette 1-4 feet and forms small white clusters of 4-petaled flowers in very early spring. The leaves also become more triangular and toothed the second year. The seed pods are long, green and narrow, and look similar to the stems.
Habitat: This plant is found in forest understories where it thrives because it flowers before trees have grown their leaves in spring. It is especially common in disturbed forest areas where people have cleared plants or trees for some purpose and may have introduced garlic mustard seeds in the process.
Negative ecological impacts: Garlic mustard outcompetes native understory plants, including tree seedlings and native wildflowers like trillium, of which several species are threatened or endangered. It spreads very rapidly due to prolific seed production and has a head start due to its two year life cycle. The rosettes that form the first year overwinter under the snow and will photosynthesize as long as the temperature is above freezing, giving it a huge head start compared to other understory plants. It also produces allelopathic compounds and releases them into the soil. These are chemicals that inhibit the growth or survival of other plants in the vicinity of garlic mustard. Some research also indicates that these compounds may inhibit beneficial fungi in the soil that help trees take up nutrients and water. Further, deer do not like to eat garlic mustard (presumably because of its strong flavor) and will aid in its infestation by preferentially grazing on other native plants (thus removing competition).
Positive attributes if any: The good news is that garlic mustard is edible. In fact, all parts of the plant are edible. The roots can be eaten and have a flavor similar to horseradish. The first year leaves are bitter but edible, and the second year leaves are pungent and apparently good for any uses including as salad greens. The shoots are supposedly also edible when they are still tender before the plant blooms in spring. So, if you’re into foraging, go pick yourself some free salad greens and help save the forest understory from this nasty invasive plant at the same time! Fair warning, garlic mustard often contains very trace amounts of cyanide, but so do many other vegetables be consider safe to eat, like broccoli! Also, make sure you’re not picking garlic mustard plants that have been treated with herbicides, which are a common method of control.
Key identifying characteristics:
- Smells like garlic when the leaves are crushed
- Tiny clusters of white flowers with 4 petals in spring
- Long stem-like green seed pods after flowering
How to report this species properly: To report his species, use this link for the Midwest Invasive Species Information Network. They’ll ask you to register (one time only) before you can report your sighting, but the good news is that once you’re registered, you’re all set to report again next time you find an invasive species! You can also learn more about invasive species using fact sheets on this site or browse their data which is pretty cool.
More Info:
Michigan.gov Invasive Species Profile
Information for foraging and eating garlic mustard
Nature Conservancy Information on life cycle and removal options
USDA National Agricultural Library Species Profile