Fruits of the yew, Taxus baccata. Each ripe fruit consists of a single seed within a fleshy red covering called an aril. The aril develops from the outer layer of the ovary, and is initially green. Several immature fruits are also visible in the picture, looking like small green acorns. Yew is a poisonous in all its parts except the fleshy red aril of the ripe seeds. The aril serves as a means to attract to birds, which disperse the seeds widely.