involucres

An involucre is a botany term describing a whorl or cluster of bracts that subtend or surround a plant structure, most often an inflorescence or a floral head. The word comes from Latin involucrum, meaning a covering or wrapper.

In the Asteraceae (the sunflower family), the flower head or capitulum is typically enclosed by an involucre of phyllaries—modified bracts arranged in one or more series around the receptacle. Phyllaries can vary in size, shape, and texture, and may be appressed to the head or more loosely arranged. The involucre can be persistent as the fruits develop or may wither away, depending on the species.

Involucres also occur in other plant groups where a ring or cup of bracts encircles an inflorescence or fruit cluster. In some cases the involucre provides protection for developing flowers or fruits; in others it participates in seed dispersal by forming a structure that aids in carrying or releasing seeds.

Functionally, involucres serve protective and often diagnostic roles. They shield developing reproductive organs from physical damage and desiccation and can influence pollinator interaction or dispersal dynamics. Because involucres and their phyllaries vary in morphology, they are frequently used as taxonomic characters to distinguish genera or species.

Overall, involucres are a key structural feature in plant anatomy, reflecting evolutionary adaptations to protect reproduction and, in some lineages, to assist in seed dispersal.