hy·pan·thi·um 
(hī-pănthē-əm)
(hī-pănthē-əm)n. pl. hy·pan·thi·a (-thē-ə)
The ringlike, cup-shaped, or tubular structure of a flower on which the sepals, petals, and stamens are borne, as in the flowers of the rose or cherry. Also called floral cup.
[New Latin : HYP(O)- + Greek anthos, flower.]
hy·panthi·al adj.