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. Under conditions of low humidity, the teeth dry out and splay away from the mouth of the capsule, thus, allowing the commonly more than 50,000 spores within to be gradually released.