Pineapple (ananas) fruit develops from:

The fruit of Ananas comosus (pineapple or ananas) is sorosis, (a type of multiple fruits), developing from spike, spadix or catkin. In this type, the flowers associate by their succulent petals, the axis bearing them grows and becomes fleshy or woody, thus, the whole inflorescence turns into a compact fruit. Here, the whole inflorescence turns into a compact fruit.