In bryophytes, a thin, hood-like tissue that forms from the archegonium and covers the developing sporophyte
b) sporophyte with foot reduced, the entire sporophyte enveloped by the calyptra, which is ± stipitate at the base.
A little hood or veil, resembling an extinguisher in form and position, covering each of the small flasklike capsules which contain the spores of mosses; also, any similar covering body