This was my first glimpse of garlic mustard. Now, to my annoyance, I see this plant almost everywhere there is some shade, particularly along roadsides and in woodland areas. It favors shaded, disturbed sites, but apparently is able to move into undisturbed woodland communities.
Some research indicates it prefers higher-pH soils.
Ecologists and wildflower enthusiasts are concerned because garlic mustard forms large stands to the exclusion of native wildflowers. Flowering stalks one to four feet in height form the following spring. Clusters of unexciting, small, white, four-petal flowers appear April through June. The leaves on the flowering stalks are triangular or heart-shaped and coarsely toothed. This is a weed to eradicate if you wish to preserve species diversity in a woodland landscape and avoid a monoculture of garlic mustard.