Hypanthium

A fruit-like body (as the rose-hip) formed by the enlargement of the torus and bearing the proper fruits on its upper or inner surface; literally "beneath the flower." Now commonly used to denote the cup-shaped receptacle on which calyx, petals and stamens are inserted in cases of perigyny, as in plum, fuchsia.^CH

This article contains a definition from the Glossary of Gardening Terms.