During the spring and summer of 2003, an inventory of vascular plants at Antietam was conducted by the University of Maryland Center for Environmental Science. Ten meter square plots were setup at forty randomly chosen locations to survey the plants in both upland habitat and habitat near streams and ponds. The plots were marked, GPS'ed and all plant species were identified and inventoried within each plot. Areas outside of the plots were also walked through to identify plant species not contained in the plots. The 2003 study identified 371 plant species at Antietam. The six most abundant species identified at this time include: Common Hackberry, Multiflora Rose, Boxelder, Japanese Honeysuckle, Garlic Mustard and Oriental Ladysthumb (aka: Bristled Knotweed or Bunchy Knotweed). Four out of these six species are exotic (non-native) plant species.
Park managers are currently working to control exotic plant species to preserver and protect native plants and restore the original habitat. Future plant research efforts will include monitoring the established sample plots, conducting an inventory of fall flowering species/ spring ephemerals, and conducting an inventory of forty new plots. Future inventories will also focus on identifying species that are common in the region but have not yet been identified in the current park inventory.