Crops and native plants across Missouri could be at risk because of an alien species of weed with a propensity for taking charge.
Garlic mustard, formally alliaria petiolata, has European origins and has long been a troublemaker in the East. Now it is cropping up more frequently in Missouri.
No one knows exactly how the seeds travel over long distances, but some seeds may have been deposited around the St. Joseph, Mo., area during the 1993 floods. "Right now it seems to be most prevalent north of the Missouri River," said Thomas Nagel, natural history regional biologist for the Missouri Department of Conservation. "It's kind of like cancer: It starts out small but spreads over an entire area." Garlic mustard can be distinguished from other woodland mustard plants by its garlic odor. It blooms in May, with its 2- to 4-feet-tall flower stalks covered with small, four-petalled, white flowers. The plant is self-pollinating. A single plant could populate an entire state. That theory played out on a small scale in Illinois during the 1980s. Six plants were found in one natural area. …