American beachgrass is the primary dune stabilizing plant of the northeastern coast of the United States. Beachgrass colonizes the high energy front slope of sand dunes and thrives under the hostile conditions of sand burial, drought and salt spray. Beachgrass serves to bind and allow accretion of sand and the building up of sand dunes. Beachgrass is however very vulnerable to catastrophic erosion due to winter storms that can result in loss of local vegetation cover and beach protection. Historic building practices on the dune line have destroyed beachgrass populations and left remnant natural populations vulnerable to erosion damage. These historic practices, coupled with the prevalence of restoration planting of the USDA developed "Cape" cultivar, have led us to try and develop methods for assessing the prevelance and spread of planted beachgrass and the effects, if any, of planted beachgrass on suspected remnant natural populations. Since beachgrass is a rhizomatous plant, it is difficult to judge genetic diversity or clonal identity. Therefore, randomly amplified polymorphic DNA (RAPD's) are being used to provide markers of genetic differentiation among beachgrass lines that are presently planted or under development by the USDA, Plant Materials Center to increase the diversity of planted beachgrass. RAPD markers have been developed that can distinguish between 7 individuals lines that were collected from Cape Cod to South Carolina. Plantings have been initiated to find out if the RAPD markers will be useful in the field to distinguish plants that have grown together in an artificial dune. Plants have also been collected from several sites that are suspected to contain high natural diversity and planted sites of suspected low natural diversity to assess whether recriutment of plants from native populations occurs over time in planted sites.

Key words: American Beachgrass, Ammophila breviligulata, RAPD