In 1988, Ptilimnium nodosum (Harperella) was listed as an endangered plant species, with only twenty-six populations remaining in the United States (USWFS, 2011). According to a survey by the Arkansas Natural Heritage Commission in 2002, there are now only ten populations of P. nodosum remaining in the country (CPC, 2010). Two of these threatened populations can be found in Washington and Alleghany counties of Maryland at Sideling Hill Creek and Fifteen Mile Creek. Harperella is a semi-aquatic wildflower that can tolerate only a specific range of habitat conditions (Bartgis, 1997). As a plant sensitive to water levels and quality, P. nodosum survival can be an indicator of the impact of human activity in the area. The goal of our study, through collaboration with the Maryland Department of Natural Resources, is to determine genetic diversity of Ptilimnium nodosum in subpopulations along Sideling Hill Creek, MD.

References
Bartgis, R. L. 1997. The distribution of the Endangered plant Ptilimnium nodosum (Rose) Mathias (Apiaceae) in the
            Potomac River drainage. Castanea 62: 55-59.
Center for Plant Conservation. 2010. CPC National Collection Profile: Ptilimnium nodosum.
            http://www.centerforplantconservation.org/collection/cpc_viewprofile.asp?CPCNum=3675.
U.S. Fish and Wildlife Service. 2011. Species profile for harperella Ptilimnium nodosum.
            http://ecos.fws.gov/speciesProfile/profile/speciesProfile.action?spcode=Q2H9.