花托筒

In angiosperms, a hypanthium or floral cup is a structure where basal portions of the calyx, the corolla, and the stamens form a cup-shaped tube. It is sometimes called a floral tube, a term that is also used for corolla tube and calyx tube. It often contains the nectaries of the plant. It is present in many plant families, although varies in structural dimensions and appearance. This differentiation between the hypanthium in particular species is useful for identification. Some geometric forms are obconic shapes, as in toyon (Heteromeles), whereas some are saucer-shaped, as in Mitella caulesc