Shifts in genetic diversity are common in plant populations after hybridization and whole genome duplication (WGD) events. We sampled plants from Spartina (syn.: Sporobolus P.M.Peterson & Saarela) populations, i.e., the hybrid Spartina x townsendii H. Groves & J. Groves (syn.: Sporobolus × townsendii P.M.Peterson & Saarela) and its genome-duplicated (allopolyploid) descendent Spartina anglica C.E. Hubbard (syn.: Sporobolus anglicus P.M.Peterson & Saarela), and performed DNA extractions for microsatellite marker analysis to determine different Spartina genotypes approximately 100 years after the introduction of the plants in the Wadden Sea area. Sampling the plants at locations along a Wadden Sea transect ranging from the southwestern part in the Netherlands to the northeastern part in Denmark. Additionally and to account for abiotic factors, which could have selective effects on genotypes, Spartina plants were sampled in different microhabitats (mudflat, pioneer zone, low marsh, pan, tidal creek) at two tidal marshes at Dieksanderkoog and Sönke-Nissen-Koog, Schleswig-Holstein, Germany. DNA was extracted from ground plant material using a modified Nucleospin Plant 2 MINI kit, with an additional centrifugation step and specific washing procedures. Normalized DNA was analyzed with FAM-labeled primers for eight SSR markers (MS02, MS07, MS13 to MS18) using a standardized PCR protocol. The PCR products were assessed via capillary electrophoresis with GeneScanTM-500 LIZ as a size standard. The microsatellite marker alleles were determined from the resulting electropherograms using GeneMapper v4.1 (Applied Biosystems, California, USA) and visually identified binning classes.