hypanthium

noun

(Gr. hypo, under; anthos: flower) (pl. hypanthia) An expansion of the receptacle of a flower that forms a saucer-shaped, cup-shaped, or tubular structure (often simulating a calyx tube) bearing the perianth (sepals and petals) and stamens at or near its rim; the hypanthium is then a cup-shaped extension of the floral axis usually formed from the union of the basal parts of the calyx, corolla, and androecium, commonly surrounding or enclosing the pistils; it may be free from or united to the ovary, as in many Myrtales. Cf. calyx tube.