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In botany, a fruit is a plant structure that contains the plant's seeds. The word fruit is used only if it comes from the part of the flower which was an ovary. It is an extra layer round the seeds, which may or may not be fleshy. However, even in botany, there is no general agreement on how fruits should be classified. Many do have extra layers from other parts of the flower.
The fleshy part of a fruit is called the mesocarp. It is between the fruit's skin (exocarp) and the seeds. The white part of an apple, for example, is the "fleshy" part of the apple. Usually, when we eat a fruit, we eat the "fleshy" part.
Types of fruits
If the entire fruit is fleshy, except for maybe a thin skin, we call the fruit a berry. A berry might contain one seed or many. Grapes, avocados, and blueberries are berries. They all have a thin skin, but most of the fruit is fleshy. Strawberries, however, are actually not berries, because the seeds are on the outside: on a real berry, the seed or seeds must be inside.
A hesperidium (pronounced hes' per id' ee uhm) is another modified berry. It has a leathery skin that is not as hard as the skin of a pepo. All citrus fruit like oranges and lemon are hesperidiums.
A pome (pohm) is a fruit that has a core surrounded by fleshy tissue that we can eat. The core is usually not eaten. Berries are different - the seeds are inside the fleshy part, not separated from it by a core. Apples and pears are pomes.
Drupes are also called stone fruit. A drupe is a fleshy fruit with a hard stone around the seed. We usually call this stone the "pit" of the fruit. Peaches and olives are drupes. Actually, the almond fruit is a drupe, too, though we eat the seed that is inside the "pit" of the almond fruit.
The botanical term includes many that are not "fruits" in the common sense of the term. such as the vegetables squash, pumpkins, cucumbers, tomato, peas, beans, corn, eggplant, and sweet pepper and some spices, such as allspice and chillies.
An accessory fruit or false fruit (pseudocarp) is a fruit in which some of the flesh is derived not from the ovary but from some adjacent tissue.
Strictly speaking, these are not botanical fruits:
- any produced by non-flowering plants, like juniper berries, which are the seed-containing female cones of conifers.
- fleshy fruit-like growths that develop from other plant tissues (like rhubarb).
Area of agreement
These are fruits which you can buy in shops, and which are also acceptable as botanical fruits:
- berry fruits: redcurrant, gooseberry, tomato, avocado
- false berries: banana, cranberry, blueberries
- stone fruits or drupes: plum, cherry, peach, apricot, olive
- citrus fruits, like oranges, grapefruits, and tangerines
- aggregate fruits: raspberries, blackberries
- multiple fruits: pineapples, figs
Many fruits come from trees or bushes. For plants, fruits are a means of dispersal, usually by animals. When the fruit breaks apart, the seeds can go into the ground and begin to grow. Most fruits we eat contain a lot of water and natural sugars, and many are high in Vitamin C. They have a large amount of dietary fibre. Fruits are usually low in protein and fat content, but avocados and some nuts are exceptions to this. Not only humans, but our closest living relatives (primates) are keen fruit-eaters. So are many other groups of herbivorous mammals and many birds.
Seedlessness is an important feature of some fruits of commerce. Commercial bananas, pineapple, and watermelons are examples of seedless fruits. Some citrus fruits, especially oranges, satsumas, mandarin oranges, and grapefruit are valued for their seedlessness.
Seedless bananas and grapes are triploids, and seedlessness results from the abortion of the embryonic plant which is produced by fertilisation. The method requires normal pollination and fertilisation.
- Mauseth, James D. 2003. Botany: an introduction to plant biology. Jones & Bartlett, Boston.
- Schlegel, Rolf 2003. Encyclopedic dictionary of plant breeding and related subjects. Haworth Press. ISBN 1-56022-950-0.
- Fulbright, Jeannie (2004). Exploring Creation with Botany. 1106 Meridian Plaza, Suite 220: Apologia Educational Ministries, Inc.. .
- Esau, K. 1977. Anatomy of seed plants. Wiley New York.
- Spiegel-Roy P. Goldschmidt E.E. 1996. The biology of citrus. Cambridge. ISBN 0-521-33321-0 p87–88