involucre

involucre is a   Noun

Definition:

[1] A whorl or set of bracts around a flower, umbel, or head.

[2] A continuous marginal covering of sporangia, in certain ferns, as in the common brake, or the cup-shaped processes of the filmy ferns.

[3] The peridium or volva of certain fungi. Called also involucrum.

Synonyms: