Botanically, a grain of rice is a fruit in disguise
In botany, a fruit is the seed-bearing structure that forms from a flower’s ovary after fertilization. Culinary speech splits fruit from vegetable by sweetness and habit, but cucumbers, pumpkins, and cereal grains such as rice or wheat are fruits by the technical definition.
Botanists define a fruit as the seed-bearing structure an angiosperm builds from its ovary once flowering is over. It begins with pollination: pollen lands on the stigma, a tube grows down the style into the ovary, and two sperm cells reach the embryo sac. One fuses with the egg to make a zygote, the future embryo; the other joins the central cell to start endosperm, the tissue that later feeds the embryo. This double fertilisation turns ovules into seeds while the ovary ripens around them.
The ovary wall, or pericarp, may turn fleshy, as in berries and drupes, or harden into the shell of a nut, and it usually splits into exocarp, mesocarp and endocarp. In some many-seeded fruits, the amount of flesh tracks how many ovules were fertilised. Where the ovary sits below other floral parts, petals, sepals and stamens can fuse with it and ripen too, producing accessory fruits such as apple, strawberry, rose hip and pineapple. Scientists sort fruits into simple, aggregate and multiple types, depending on whether they come from one pistil, several pistils in one flower, or a cluster of flowers, though these groups say nothing about evolutionary kinship.
The kitchen draws different lines. Cooks call sweet or sour produce fruit and savoury produce vegetables, yet cucumbers, pumpkins, beans, peas, peanuts, corn, aubergine, peppers and tomatoes are all botanical fruits, as are spices such as black pepper, cumin and allspice. A nut counts as a fruit rather than a seed. Rhubarb goes the other way: baked into pies as a fruit, it is really a leaf stalk. Rice and wheat grains are fruits called caryopses, but their thin wall is fused to the seed coat, so nearly everything we eat of them is seed.
Fruits exist to spread seeds, and edible ones strike a bargain with animals, including people, who gain food while carrying seeds away. That partnership has made fruit a large share of global farm output, and apples and pomegranates have gathered rich symbolic meanings.
Source: Fruit
