in antiquity. See Disc.

botany, the middle part of a radiated compound flower, generally consisting of small florets, with a hollow regular petal. It is commonly surrounded by large, plain, or flat, tongue-shaped petals, in the circumference or margin; as in daffy, groundsel, and leopards bane; sometimes the circumference is naked, as in cotton-weed and some species of coltsfoot.

Discus folii, the surface of the leaf.