The assemblages of myxomycetes associated with the three types of temperate grasslands (tall grass, mixed grass and short grass) found across the western central United States were examined by collecting samples for isolation of these organisms from nine study sites. Samples consisted of two types of ground litter, two types of aerial litter (dead but still attached plant parts) and dung. These were brought back to the laboratory and used to prepare a series of moist chamber cultures. These cultures yielded 1,301 collections of myxomycetes representing 59 species in 18 genera. Some collections could be identified only to genus and one in particular ( Lepidoderma sp.) appears to be an undescribed taxon. Physarum spectabile was recorded for the first time in North America. Overall, only eight species ( Badhamia melanospora , Didymium anellus , D . difforme , D . squamulosum , Perichaena depressa , Physarum cinereum , P . pusillum , and Stemonitis fusca ) were recovered from all nine study sites and thus are considered to represent a core component of the myxomycete biota of temperate grasslands.