allows for gradual spore discharge, instead of releasing them all at once.
At the tip of the capsule is a lid (operculum) which, prior to spore dissemination, falls away exposing the so-called peristome teeth, a set of structures, often delicate and thread-like in appearance, that form a ring around the mouth (rim) of the capsule (c). The peristome teeth are perhaps the most characteristic feature of the mosses; usually composed of cell wall remnants, they respond to changes in the humidity of the atmosphere.