1) Buccula 2) Chin 1) Plant part 2) Plant structure 
The mentum is an anatomical structure, a projecting feature that is near the mouth of any of a variety of different kinds of animals: ...
a chin or pouch like extension formed by the column foot and the bases of the lateral sepals being united
the chin
• (n.) The front median plate of the labium in insects. See Labium.
A chin-like extension at the base of a flower consisting of the column-foot fused with the bases of the lateral sepals.
(men´tәm) Latin word meaning chin; a term used in anatomy.
Men'tum noun [ Latin , chin.] (Zoology) The front median plate of the labium in insects. See Labium . 
Type: Term Pronunciation: men′tŭm, -tī Synonyms: chin
Mentum: Medical term for the chin. From Latin. See: Chin.
a chin or pouch like extension formed by the column foot and the bases of the lateral sepals being united
In anatomy, the mentum is the anterior and inferior mandible of the lower jaw.
[n] - a projection like a chin formed by the sepals and base of the column in some orchids 2. [n] - a projection below the mouth of certain mollusks that resembles a chin
noun a projection below the mouth of certain mollusks that resembles a chin
chin, the front median plate of the labium in insects
a chin-like projection formed by the sepals and extended foot of the column