Apple, (Malus domestica), fruit of the domesticated tree Malus domestica (family Rosaceae), one of the most widely cultivated tree fruits. The apple is a pome (fleshy) fruit, in which the ripened ovary and surrounding tissue both become fleshy and edible. The apple flower of most varieties requires cross-pollination for fertilization. When harvested, apples are usually roundish, 5–10 cm (2–4 inches) in diameter, and some shade of red, green, or yellow in colour; they vary in size, shape, and acidity depending on the variety.
