Questions: Is the incidence of root hemiparasitic plants in non-forest vegetation associated with high diversity? Are root hemiparasites more associated with species-rich vegetation than other species? - Location: Czech Republic. - Methods: Plot size-corrected species richness, Shannon diversity and Pielou's evenness were computed for a representative set of 18 101 vegetation plots rep-resenting all main types of terrestrial open (non-forest) habitats of the country.Null models of species richness assuming occurrence of a random species withgiven occurrence frequency, reflecting higher incidence probability in species-rich plots, were constructed for 16 common root hemiparasitic species. The nullmodel distribution of species richness was subsequently compared with theactual mean species richness of plots containing the respective root hemipara-sites. Median values of plot Shannon diversity and evenness were computed foreach species in the database. Values obtained for plots containing individual roothemiparasites were compared with distribution of values for other species in thedatabase. - Results: The occurrence of 11 of 16 root hemiparasites studied was associatedwith high species richness significantly more than under random expectations;three species were negatively associated. Three root hemiparasites were amongthe top 5% of all species associated with high species richness and Shannondiversity, and eight were among the top 25%. Almost 50% of the top 1% mostspecies-rich plots contained at least one root hemiparasitic species. - Conclusions: We demonstrated a positive association between the incidence ofmost root hemiparasites and diversity of non-forest terrestrial plant communi-ties at a broad landscape scale. This finding scales up the results of experimentalstudies that showed some root hemiparasites act as ecosystem engineers,increasing vegetation diversity.