AbstractThe growth of transplants of sixSphagnumspecies at a blanket bog site in the southern Pennines was investigated and compared with that of similar transplants of the same provenance at a site in the Berwyn Mountains, North Wales. All species made some growth in the first year at the polluted southern Pennine site, but onlySphagnum recurvumgrew in the second year. All species made good growth in both years at the relatively unpolluted North Wales site. A similar result was obtained in a later transplant experiment, and after more than 3 years,Sphagnum recurvumalone survives of the original transplants in the southern Pennines. The failure of these transplants is discussed in relation to a fumigation experinlent in whichSphagnumspecies were subjected to concentrations of sulphur dioxide in air and sulphate in rain similar to those occurring in the southern Pennines today. It is concluded that current concentrations of sulphur pollutants may not entirely account for the failure of the transplants.