How have studies of ancient DNA from sediments contributed to the reconstruction of Quaternary floras?

Ancient DNA (aDNA) from lake sediments, peats, permafrost soils, preserved megafaunal gut contents and coprolites has been used to reconstruct late-Quaternary floras. aDNAis either used alone for floristic reconstruction or compared with pollen and/or macrofossil results. In comparative studies, aDNA may complement pollen and macrofossil analyses by increasing the number of taxa found. Wediscuss the relative contributions of each fossil group to taxon richness and the number of unique taxa found, and situations in which aDNA has refined pollen identifications. Pressing problems in aDNA studies are contamination and ignorance about taphonomy (transportation, incorporation, and preservation in sediments). Progress requires that these problems are reduced to allow aDNA to reach its full potential contribution to reconstructions of Quaternary floras.