aril A usually fleshy and often brightly coloured outgrowth from the funicle or hilum of a seed, a third integument. Arils probably often aid seed dispersal, by drawing attention to the seed after the fruit has dehisced, and by providing food as an attractant and reward to the disperser. The aril of the nutmeg (see MYRISTICA) produces the spice mace, and the seed itself is the nutmeg.

ar·il / ˈarəl/ • n. Bot. an extra seed-covering, typically hairy or fleshy, e.g., the red fleshy cup around a yew seed.DERIVATIVES: ar·il·late / -lit; -ˌlāt/ adj.

aril An outgrowth that grows around and may completely enclose the testa (seed coat) of a seed. It develops from the placenta, funicle, or micropyle of an ovule. The aril surrounding the nutmeg seed forms the spice mace. See also caruncle.