Why is apple called a false fruit? Which part(s) of the flower forms the fruit?

Fruits produced by organs other than the ovary. False fruits are those in which the accessory floral part, in addition to the ovary, contributes to fruit formation.

In the case of apples, the thalamus and the ovary develop the majority of the fleshy part. The main edible part of an apple is the fleshy receptacle.

False fruits are also known as spurious fruits, pseudofruit, or pseudocarp. A false fruit is one that has some of its flesh derived not from the floral ovary but from tissue outside the carpel. The false fruit can enclose a flower from the flower's cup. The thalamus, not the ovary, develops the majority of the fleshy portion of the apple. False fruits can sometimes develop from calyx parts. False fruits are parthenocarpic, meaning they develop without fertilization and lack seeds.

The pericarp of the ovary wall is present in true fruits. The seeds are produced as a result of fertilization. False fruits can be apples, strawberries, coconuts, mangos, and so on.

In the case of apples, the thalamus and the ovary develop the majority of the fleshy part. This is the reason it is called as false fruit. Ovary is the part of the flower that forms fruit.