A review of NPS species, the national database registering plant occurrence in parks, indicated that 465 plant species occurred in Hopewell Culture National Historical Park. Of these, 148 (32%) are non-native, meaning that these plants were recently introduced through human agency. The authors detail the status of invasive plants and the resource management issue(s) for the park.

The authors conducted a second year of invasive plant surveys at Lincoln Boyhood National Memorial. This allowed a comparison of invasive plant species found in 2006 to those found in 2011. their findings are detailed in this publication.