Hair-cap mosses comprise the genus Polytrichum of the order Polytrichales. Both the genus and common name of these mosses make reference to the hairy calyptra characteristic of the sporophyte capsules (sporangia) before they reach maturity. The capsules are very conspicuous, extending seveal inches into the air on long, narrow stalks and appearing similar to grains of wheat, causing some individuals to alternatively refer to the mosses as pigeon wheat. The calyptra forms from the wall of tissue that encases the archegonium of a female shoot present during the gametophyte stage of the moss life cycle. Before the spores are released from a capsule, the operculum and calyptra are shed and the numerous peristome teeth around the mouth of the sporangium slowly uncurl. The spores are dispersed by the wind and germinate when they reach a suitable environment.