The sporogonium of Funaria is composed of the apophysis, theca and operculum. The peristome lies immediately underneath the operculum. It consists of two sets of long conical teeth. There are sixteen teeth in each set (the total being 32). The teeth of both sets are on the same radii and thus opposite to each other. The peristome teeth close the opening of the spore sac. The teeth of the outer set respond to changes in the humidity and thus are said to be hygroscopic. The inner peristome teeth do not show hygroscopic movement.