On the left is a longitudinal section through the inflorescence of a European chestnut (Castanea sativa). Three female flowers can be seen surrounded by many bracts forming the involucre.

On the right is an involucre of an American chestnut (Castanea dentata) that has opened to show the several nuts inside. In this species of chestnut, the bracts of the involucre are covered with many fine spines.

The "cup" that surrounds an oak acorn is also an involucre.