- (in prescriptions) plural of .
noun, plural gra·na [grey-nuh] /ˈgreɪ nə/.
- (in prescriptions) a grain.
- Botany. one of the structural units of a chloroplast in vascular plants, consisting of layers of thylakoids.
Plural grana (grā′nə)
- A stacked membranous structure within the chloroplasts of plants and green algae that contains the chlorophyll and is the site of the light reactions of photosynthesis. The saclike membranes that make up grana are known as thylakoids. See more at chloroplast.