What Exactly Is a Fruit?
Some foods we commonly think of as vegetables, such as the tomato or pea
pod, are actually, botanically speaking, fruits. Peppers, squash, eggplant,
cucumber, and sweet corn are also technically fruits. Fruits are formed after
fertilization as the ovary ripens; while it develops, the other flower parts wither
and die. The wall of the ovary becomes the pericarp (the outer layer of the
fruit) and the fertilized ovules turn into seeds. Fruits can be fleshy or dry.
The drupes (olive, plum, cherry) develop from a single ovary with a single
ovule that becomes the pit. Pome fruits (apple, pear) grow from a compound
ovary with many ovules and have distinct chambers with many seeds. Berries
(tomato, pepper, grape) also have many seeds. Pepo fruits (melon, pumpkin,
squash, cucumber) are fleshy with many seeds and a hard rind. Raspberries,
strawberries, and blackberries are fleshy aggregate fruits that form from the
fusion of many flowers. Parthenocarpic fruits do not develop seeds and can
occur naturally (banana) or be chemically induced (oranges, watermelon).
Dry fruits that break open to free the seeds while still attached to the plant are
described as dehiscent. Some examples are legumes (pea pod), which develop
from a single ovary that splits down both sides and capsules that grow from
a compound ovary and open at the top (poppy). The pericarp of indehiscent
fruits remains closed until after it falls off the plant; examples of these types
of fruits are corn and nuts.