calyptra calyx operculum calyx (exact) plant_anatomy Sometimes found in Eucalyptus and other Myrtaceae, covering an inner operculum or calyptra corolla. The sepals are generally completely fused. Species of the subgenus Monocalyptrus have only a calyptra corolla (inner operculum) while in most other species, a calyptra calyx is also present, at least early in flower development. Not the same structure as a spore capsule calyptra or fruit operculum. Sometimes erroneously referred to as part of a fruit. calycine operculum (exact) caliptra c&#225liz (Spanish, exact) rwalls 2011-09-15T02:56:37Z 蘚帽がく (Japanese, exact) calyx calyptrae (exact, plural) outer operculum (exact) A fused calyx (PO:0025582) that is composed of fused sepals (PO:0025584). PO:0025329 fused calyx