Pistils are made of carpels which are megasporophylls.
The part of the pistil containing the ovules is the ovary. Fruits
are ripened ovaries. One of the definitive characters of the
angiosperms is that the ovules are encased. Fruits always serve
to protect the maturing ovules/seeds. However, a great deal of
variation exists in the angiosperms in regards to the nature of
the mature fruit.
Berries: Fruits that are totally fleshy are berries. Many
unrelated plants have fruits that are berries. Commonly, berries
attract animals that eat the fruit and swallow the seeds
whole.
Drupes: Fruits that have a fleshy outer and a stony inner part are drupes. "Stone fruits" are drupes, and include cherries, peaches, plums, apricots and nectarines. All are members of the genus Prunus in the family Rosaceae. Other plants bear drupes as well but are unrelated. This is another example of convergent evolution.
Pomes: Pomes are a particular type of fruit borne by a group of plants in the Rosaceae including apple, pear, hawthorne and quince. In pomes the sepal, petal and stamen tissues have become fused to the ovary resulting in an inferior ovary. Pomes, like berries, are fleshy, but the tissues surrounding the ovary contributes the bulk of the flesh of the mature fruit.
Follicles: Follicles are dehiscent dry fruits derived from a simple carpel with one suture. The one obvious example familiar to many people are milkweed fruits.
Legumes: Like pomes this fruit type is associated with a taxonomic group - the bean family (Fabaceae). This fruit is derived from one carpel with two sutures. Note that peanuts are not dehiscent but are still considered to be legumes.
Capsules: A capsule is any dehiscent fruit derived from a compound ovary.
Grains, Nuts, Achenes: These are all examples of fruits that are non-dehiscent and develop into a hard or stony tissue surrounding the seed.
Grains are the fruits of grasses (Poaceae). The carpel develops into a hard layer tightly fused to the seed coat. This covering is the bran stripped from the wheat kernel.
Nuts are fruits where the carpel becomes completely stony. Many fruits considered to be nuts, however, are actually drupes such as walnut, almond and coconut. Acorns are true nuts.
Achenes are hard fruits but not stony. An examples is sunflower "seed". Some achenes are winged and these are termed samaras.
Aggregate Fruits: Some flowers have multiple pistils. Their fruits develop into aggregates of simple fruits all attached to the receptacle of the flower. These
Multiple Fruits: Some plants have fruits that develop from whole inflorescences - from flower stalks. Examples include figs, mulberries, osage oranges, and pineapple.