Term:

Ring nectary (= nectary ring-like)
Definition:

A raised, circular ridge found between the attachment of the androecium and the base of the style that produces nectar.
Notes:

Ring-line structures surround the ovary in at least some species of Grias and some species of zygomorphic-flowered Lecythidaceae. We emphasize that we have not had any field demonstrations that confirm that these structures actually produce nectar.