Calyptra
Calyptra (kȧ*lip"trȧ) , noun
[New Latin, from Greek kaly`ptra a covering for the head, from kaly`ptein to cover.]
(Botany) 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.