Certain Antarctic moss communities often have a pattern of concentric arcs or rings on their surfaces which can be up to 5 m in diameter. These are caused by fungal infection and show many similarities to those previously reported from the Arctic. The fungus appears not to spread through the moss uniformly but in a series of rapid advances, resulting in parallel stripes of infected moss; the reasons for this pattern remain unclear. During the seasons studied 2–6 infection stripes were produced per year, resulting in an average rate of advance of 8 cm yr−1. Three species of ascomycete have been found associated with these rings.