In botany, an operculum or calyptra is a cap-like structure in some flowering plants, mosses, and fungi. It is a covering, hood or lid, describing a feature in plant morphology.
Red operculum of Eucalyptus erythrocorys
Operculum and scar of Eucalyptus blakelyi
Calyptra of Tortula muralis
Calyptra on top of the brown spore capsule (sporophyte) of the moss Physcomitrella patens. The brownish archegonial venter is still visible.
Corymbia, commonly known as bloodwoods, is a genus of about one hundred species of tree that, along with Eucalyptus, Angophora and several smaller groups, are referred to as eucalypts. Until 1990, cor