Garlic mustard is an invasive plant from Europe and Asia, and it is a bit of a landscape pest in the woods of the mid-Atlantic region (and throughout eastern North America.) While initially introduced for herbal and medicinal qualities, it spread rapidly due to a lack of natural predators. Its leaves have a garlicky smell when crushed, which gives it its common name. First-year plants are characterized by low-growing leaves, while second-year plants demonstrate "bolt" form, growing up to 3 feet high and topped with white, four-petaled flowers. The plant is most easily controlled by pulling—the taproot does not regrow when broken. It should be pulled before seeds can develop. It is visible throughout the wooded landscape at Glenstone, though the grounds team does do seasonal work to pull prominent populations.

–Kevin McDonald