Total mercury (THg) and methylmercury (MMHg) were investigated in 259 wild plants belonging to 49 species in 29 families that grew in heavily Hg-contaminated wastelands composed of cinnabar ore mine tailings (calcines) in the Wanshan region, southwestern China, the world's third largest Hg mining district. The bioconcentration factors (BCFs) of THg and MMHg from soil to roots ([THg](root)/[THg](soil), [MMHg](root)/[MMHg](soil)) were evaluated. The results showed that THg and MMHg in both plants and soils varied widely, with ranges of 0.076-140 mu g/g THg and 0.19-87 ng/g MMHg in roots, 0.19-106 mu g/g THg and 0.06-31 ng/g MMHg in shoots, and 0.74-1440 mu g/g THg and 0.41-820 ng/g MMHg in soil. Among all investigated species, Arthraxon hispidus, Eremochloa ciliaris, Clerodendrum bunge, and Ixeris sonchifolia had significantly elevated concentrations of THg in shoots and/or roots that reached 100 mu g/g, whereas Chenopodium glaucum, Corydalisedulis maxim, and Rumex acetosa contained low values below 0.5 mu g/g. In addition to the high THg concentrations, the fern E. ciliaris also showed high BCF values for both THg and MMHg exceeding 1.0, suggesting its capability to extract Hg from soils. Considering its dominance and the tolerance identified in the present study, E. ciliaris is suggested to be a practical candidate for phytoextraction, whereas A. hispidus is identified as a potential candidate for phytostabilization of Hg mining-contaminated soils.