Term:

External flap
Definition:

A flap that extends outward from the inner coil of the androecium to cover at least part of the top of the androecial hood. This structure is only fully developed in species of Couratari although incipient external flaps are found in several species of Eschweilera (e.g., Eschweilera cyathiformis and E. ovalifolia). In these species, the furrow is called the ligular sulcus.
Notes:

This character is one of the defining features of all species of Couratari.