'Calyptra' definitions:

Definition of 'calyptra'

noun

The hood or cap covering the calyx of certain plants: e.g., the California poppy

From: GCIDE

Calyptra \Ca*lyp"tra\ (k[.a]*l[i^]p"tr[.a]), n. [NL., fr. Gr. kaly`ptra a covering for the head, fr. kaly`ptein to cover.] (Bot.) 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. [1913 Webster]