Operculum (botany)

The flower buds of Eucalyptus erythrocorys have a large, bright red operculum.

An operculum or (in plural) opercula are botanical terms describing a certain structure or structures of certain vascular plants, mosses, or fungi which act as a cap, flap, or lid. In vascular plants, an operculum may also be called a bud cap.

Examples of structures identified as opercula include:

• A flap of the sporangium of a moss, covering the peristome (appendages surrounding the mouth of a moss capsule).
• The cap of the ascus in certain ascomycetous fungi.
• A lid covering the aperture of pollen grains.
• The bud cap covering the flowers of Eucalyptus and Corymbia trees which falls off as they open.
• The covering of a pyxidium (fruit capsule whose upper part falls off when the seeds are released) of a plant, such as the plantain.
• The flared leaflet that prevents a pitcher plant from accumulating rainwater.

See also

• Operculum (disambiguation)