facets is a form of:

Involucre



ENGLISH MEANING
noun
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.