Arsenic redox transformations and cycling in the rhizosphere of Pteris vittata and Pteris quadriaurita

•Pteris vittata (PV) and Pteris quadriaurita (PQ) were grown in As-rich soil.•PV translocated four times more As from soil to fronds than PQ.•Labile AsIII/AsV imaging revealed sub-mm As redox transformations along PV roots.•PV used AsIII efflux for avoiding root As toxicity while PQ did not.•Closely-related As-accumulating ferns have distinct mechanisms for As uptake.