Involucre

An involucre of bracts surrounds the inflorescence of Protea cynaroides.

In general, an involucre is a covering. It may refer to:

• in flowering plants: an involucral bract, or a pair, whorl or other collection of such bracts, surrounding an inflorescence, particularly in:
  • Asteraceae (Compositae)
  • Apiaceae (Umbelliferae)
  • Euphorbiaceae
  • Proteaceae
• in some fungi: the involucrum, peridium or volva
• in Marchantiophyta (liverworts), a short tube surrounding one or more antheridia or archegonia or a developing sporophyte
• in the fern family Hymenophyllaceae: the cup-shaped indusium surrounding a cluster of sporangia
• in the Fagaceae: a term sometimes misused for the cupule surrounding developing nuts (e.g., the cap of an acorn)

Wikisource has the text of The New Student's Reference Work article Involucre.