Is pineapple a fruit?

The pineapple “fruit” is not really a fruit at all but is a mass of individual berries fused to the central stalk. This is why the “fruit” has leaves on top. They are actually the continued growth of the stalk beyond where the berries are attached.

Pineapples are not grown from seed. The important commercial cultivars such as ‘Smooth Cayenne’ from Hawaii and ‘Red Spanish’ from the West Indies are self-sterile – the inconspicuous flowers are not capable of fertilizing their own eggs. Unless different cultivars are grown near each other (an unlikely occurrence in commercial plantations), the resulting fruits are seedless (parthenocarpic). Pineapples are readily reproduced by vegetative propagation, using crowns, slips, or suckers. The crown is the vegetative shoot on top of the fruit, and new plants take 2 years to produce fruit. Slips are side shoots from just below the fruit. Plants from slips take 20 months to produce fruit. Suckers are side shoots that develop from the main stem at ground level, and take 17 months to produce fruit.
Each plant that is propagated produces one fruit at the top of its stem. This high quality fruit is called the “plant” crop. After the fruit is harvested, several suckers develop and one year later produce the “ratoon” crop. The fruits are smaller and of lesser quality. A second ratoon crop can develop after the first crop is harvested. After that, the field is dug up and replanted.
Pineapple fruit quality is at its best only if the fruit matures on the plant. They do not become sweeter if harvested earlier since there are no starch reserves to be converted to sugar. The sugar content must come from the rest of the plant.
Pineapples are 15% sugar along with malic and citric acids. In areas near where it is grown, a pineapple wine is fermented. It does not store well so it is rarely seen outside of the tropics. Pineapples also contain bromelain, a protein digesting and milk-clotting enzyme similar to pepsin. Bromelain is used commercially to tenderize meat and chill-proof beer. The bromelain may account for the belief that pineapples are good for our digestion.