According to literature, the manganese content of most basidiomycetes fluctuates between 10 and 60 mg/kg, whereas the iron levels range from 100-500 mg/kg (both expressed on dry weight). The present authors report that bioconcentration of manganese is a distinguishing feature of the Panaeoloideae, as demonstrated by the analysis of 44 collections representing 15 taxons. Carpophores generally contain between 250 and 2500 mg/kg on dry weight, and, with the notable exception of Panaeolus semiovatus, P. antillarum and P. phalaenarum, their iron content is 2 to 3 times lower. This phenomenon was not observed in members of related genera such as Psathyrella and Coprinus.