Fruit anatomy
Encyclopedia
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
, the mature ovary
Ovary (plants)
In the flowering plants, an ovary is a part of the female reproductive organ of the flower or gynoecium. Specifically, it is the part of the pistil which holds the ovule and is located above or below or at the point of connection with the base of the petals and sepals...
or ovaries from one or more flowers. In fleshy fruits, the outer and often edible layer is the pericarp, which is the tissue that develops from the ovary wall of the flower and surrounds the seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
s. Some edible "vegetables" such as the cucumber
Cucumber
The cucumber is a widely cultivated plant in the gourd family Cucurbitaceae, which includes squash, and in the same genus as the muskmelon. The plant is a creeping vine which bears cylindrical edible fruit when ripe. There are three main varieties of cucumber: "slicing", "pickling", and...
, squash, and tomato
Tomato
The word "tomato" may refer to the plant or the edible, typically red, fruit which it bears. Originating in South America, the tomato was spread around the world following the Spanish colonization of the Americas, and its many varieties are now widely grown, often in greenhouses in cooler...
es are actually botanical
Botany
Botany, plant science, or plant biology is a branch of biology that involves the scientific study of plant life. Traditionally, botany also included the study of fungi, algae and viruses...
fruits. In some seemingly pericarp fruits the edible portion is not derived from the ovary, for example in Ackee
Ackee
The ackee, also known as the vegetable brain, achee, akee apple or akee is a member of the Sapindaceae , native to tropical West Africa in Cameroon, Gabon, São Tomé and Príncipe, Benin, Burkina Faso, Côte d'Ivoire, Ghana, Guinea, Guinea-Bissau, Mali, Nigeria, Senegal, Sierra Leone and Togo.It is...
the edible portion is an aril
Aril
An aril is any specialized outgrowth from the funiculus that covers or is attached to the seed. It is sometimes applied to any appendage or thickening of the seed coat in flowering plants, such as the edible parts of the mangosteen and pomegranate fruit, the mace of the nutmeg seed, or the...
, and in pineapple
Pineapple
Pineapple is the common name for a tropical plant and its edible fruit, which is actually a multiple fruit consisting of coalesced berries. It was given the name pineapple due to its resemblance to a pine cone. The pineapple is by far the most economically important plant in the Bromeliaceae...
several tissues from the flower and the stem are involved.
Categories of fruits
Fruits come in three main anatomical categories:- Simple fruits are formed from a single ovary and may contain one to many seeds. They can be either fleshy or dry. Examples of simple fleshy fruits are berriesBerryThe botanical definition of a berry is a fleshy fruit produced from a single ovary. Grapes are an example. The berry is the most common type of fleshy fruit in which the entire ovary wall ripens into an edible pericarp. They may have one or more carpels with a thin covering and fleshy interiors....
, drupeDrupeIn botany, a drupe is a fruit in which an outer fleshy part surrounds a shell of hardened endocarp with a seed inside. These fruits develop from a single carpel, and mostly from flowers with superior ovaries...
s, and pomePomeIn botany, a pome is a type of fruit produced by flowering plants in the subfamily Maloideae of the family Rosaceae.A pome is an accessory fruit composed of one or more carpels surrounded by accessory tissue...
s. Examples of dry fruits include nutNut (fruit)A nut is a hard-shelled fruit of some plants having an indehiscent seed. While a wide variety of dried seeds and fruits are called nuts in English, only a certain number of them are considered by biologists to be true nuts...
s and grainsCaryopsisIn botany, a caryopsis is a type of simple dry fruit — one that is monocarpelate and indehiscent and resembles an achene, except that in a caryopsis the pericarp is fused with the thin seed coat....
.
- Aggregate fruits are formed from a single compound flower and contain many ovaries. Examples include raspberriesRaspberryThe raspberry or hindberry is the edible fruit of a multitude of plant species in the genus Rubus, most of which are in the subgenus Idaeobatus; the name also applies to these plants themselves...
and blackberriesBlackberryThe blackberry is an edible fruit produced by any of several species in the Rubus genus of the Rosaceae family. The fruit is not a true berry; botanically it is termed an aggregate fruit, composed of small drupelets. The plants typically have biennial canes and perennial roots. Blackberries and...
.
- Multiple fruitMultiple fruitMultiple fruits are fruits that are formed from a cluster of flowers . Each flower in the inflorescence produces a fruit, but these mature into a single mass...
s are formed from the fused ovaries of multiple flowers. An example for a multiple fruit is pineapplePineapplePineapple is the common name for a tropical plant and its edible fruit, which is actually a multiple fruit consisting of coalesced berries. It was given the name pineapple due to its resemblance to a pine cone. The pineapple is by far the most economically important plant in the Bromeliaceae...
.
Anatomy of simple fruits
Accessory fruit
An accessory fruit is a fruit in which some of the flesh is derived not from the ovary but from some adjacent tissue exterior to the carpel. Examples of accessory tissue are the receptacle of strawberries, figs, or mulberries, and the calyx of Gaultheria procumbens or Syzygium jambos...
s, other tissues develop into the edible portion of the fruit instead, for example the receptacle of the flower in apples and strawberries.
Pericarp layers
The pericarp itself is typically made up of three distinct layers: the exocarp, which is the most-outside layer or peelPeel (fruit)
Peel, also known as rind or skin, is the outer protective layer of a fruit or vegetable which could be peeled off. The rind is usually the botanical exocarp, but the term exocarp does also include the hard cases of nuts, which are not named peels since they are not peeled off by hand or peeler, but...
, the mesocarp, which is the middle layer or pith
Pith
Pith, or medulla, is a tissue in the stems of vascular plants. Pith is composed of soft, spongy parenchyma cells, which store and transport nutrients throughout the plant. In eudicots, pith is located in the center of the stem. In monocots, it extends also into flowering stems and roots...
, and the endocarp, which is the inner layer surrounding the hollowed ovary or the containing seeds.
Endopericarpal layer
The endopericarpal layer is the layer between the endocarp and the hemispherical diploid organism.Exocarp
Exocarp (Gr. "outside" + "fruit"), is a botanical term for the outermost layer of the pericarp (or fruit). The exocarp forms the tough outer skin of the fruit, which bears oil glands and pigments. The exocarp is sometimes called the epicarp, or, especially in citrusCitrus
Citrus is a common term and genus of flowering plants in the rue family, Rutaceae. Citrus is believed to have originated in the part of Southeast Asia bordered by Northeastern India, Myanmar and the Yunnan province of China...
es, the flavedo.
Cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
but also contains other components, such as essential oil
Essential oil
An essential oil is a concentrated hydrophobic liquid containing volatile aroma compounds from plants. Essential oils are also known as volatile oils, ethereal oils or aetherolea, or simply as the "oil of" the plant from which they were extracted, such as oil of clove...
s, paraffin waxes, steroid
Steroid
A steroid is a type of organic compound that contains a characteristic arrangement of four cycloalkane rings that are joined to each other. Examples of steroids include the dietary fat cholesterol, the sex hormones estradiol and testosterone, and the anti-inflammatory drug dexamethasone.The core...
s and triterpenoid
Triterpenoid
Triterpenoids are terpenoid derviatives of triterpene molecules.They may have useful anti-cancer properties.Notable examples*Betulinic acid, possible anti-cancer drug*Bardoxolone methyl, inflammation modulator*Triterpenoid saponins...
s, fatty acid
Fatty acid
In chemistry, especially biochemistry, a fatty acid is a carboxylic acid with a long unbranched aliphatic tail , which is either saturated or unsaturated. Most naturally occurring fatty acids have a chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually derived from...
s, pigment
Pigment
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
s (carotenoid
Carotenoid
Carotenoids are tetraterpenoid organic pigments that are naturally occurring in the chloroplasts and chromoplasts of plants and some other photosynthetic organisms like algae, some bacteria, and some types of fungus. Carotenoids can be synthesized fats and other basic organic metabolic building...
s, chlorophyll
Chlorophyll
Chlorophyll is a green pigment found in almost all plants, algae, and cyanobacteria. Its name is derived from the Greek words χλωρος, chloros and φύλλον, phyllon . Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light...
s, flavonoid
Flavonoid
Flavonoids , are a class of plant secondary metabolites....
s), bitter principles (limonene
Limonene
Limonene is a colourless liquid hydrocarbon classified as a cyclic terpene. The more common D isomer possesses a strong smell of oranges. It is used in chemical synthesis as a precursor to carvone and as a renewably-based solvent in cleaning products....
), and enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
s.
In citrus fruits, the flavedo constitutes the peripheral surface of the pericarp. It is composed of several cell layers that become progressively thicker in the internal part; the epidermic
Epidermis (botany)
The epidermis is a single-layered group of cells that covers plants' leaves, flowers, roots and stems. It forms a boundary between the plant and the external environment. The epidermis serves several functions, it protects against water loss, regulates gas exchange, secretes metabolic compounds,...
layer is covered with wax and contains few stoma
Stoma
In botany, a stoma is a pore, found in the leaf and stem epidermis that is used forgas exchange. The pore is bordered by a pair of specialized parenchyma cells known as guard cells that are responsible for regulating the size of the opening...
ta, which in many cases are closed when the fruit is ripe.
When ripe, the flavedo cells contain carotenoids (mostly xanthophyll
Xanthophyll
Xanthophylls are yellow pigments that form one of two major divisions of the carotenoid group. The name is from Greek xanthos + phyllon , due to their formation of the yellow band seen in early chromatography of leaf pigments...
) inside chromoplast
Chromoplast
Chromoplasts are plastids responsible for pigment synthesis and storage. They, like all other plastids , are organelles found in specific photosynthetic eukaryotic species....
s, which, in a previous developmental stage, contained chlorophyll
Chlorophyll
Chlorophyll is a green pigment found in almost all plants, algae, and cyanobacteria. Its name is derived from the Greek words χλωρος, chloros and φύλλον, phyllon . Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light...
. This hormonally controlled progression in development is responsible for the fruit's change of color from green to yellow upon ripening.
The internal region of the flavedo is rich in multicellular bodies with spherical or pyriform shapes, which are full of essential oils.
Mesocarp
Mesocarp (Gr. "middle" + "fruit") or Sarcocarp ("flesh" + "fruit"), is the botanical term for the succulent and fleshy middle layer of the pericarp of drupaceousDrupe
In botany, a drupe is a fruit in which an outer fleshy part surrounds a shell of hardened endocarp with a seed inside. These fruits develop from a single carpel, and mostly from flowers with superior ovaries...
fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
, between the exocarp and the endocarp; it is usually the part of the fruit that is eaten.
This term may also refer to any fruit that is fleshy throughout. In a hesperidium
Hesperidium
A hesperidium is a modified fruit with a tough, leathery rind. The peel contains volatile oil glands in pits. The fleshy interior is composed of separate sections, called carpels, filled with fluid-filled vesicles that are actually specialized hair cells.The outer ovary wall becomes the thick...
such as a citrus
Citrus
Citrus is a common term and genus of flowering plants in the rue family, Rutaceae. Citrus is believed to have originated in the part of Southeast Asia bordered by Northeastern India, Myanmar and the Yunnan province of China...
fruit, the mesocarp is also referred to as albedo or pith
Pith
Pith, or medulla, is a tissue in the stems of vascular plants. Pith is composed of soft, spongy parenchyma cells, which store and transport nutrients throughout the plant. In eudicots, pith is located in the center of the stem. In monocots, it extends also into flowering stems and roots...
because of its soft fiber. It is part of the peel
Peel (fruit)
Peel, also known as rind or skin, is the outer protective layer of a fruit or vegetable which could be peeled off. The rind is usually the botanical exocarp, but the term exocarp does also include the hard cases of nuts, which are not named peels since they are not peeled off by hand or peeler, but...
which is commonly removed by hand.
Endocarp
Endocarp (Gr. "inside" + "fruit"), is a botanical term for the inside layer of the pericarp (or fruit), which directly surrounds the seedsSEEDS
SEEDS is a voluntary organisation registered under the Societies Act of India....
. It may be membranous as in citrus
Citrus
Citrus is a common term and genus of flowering plants in the rue family, Rutaceae. Citrus is believed to have originated in the part of Southeast Asia bordered by Northeastern India, Myanmar and the Yunnan province of China...
where it is the only part consumed, or thick and hard as in the stone fruits
Stone fruits
Stone fruits , in botany, refers to drupe, fruits in which an outer fleshy part surrounds a shell of hardened endocarp with a seed inside. These fruits develop from a single carpel, and mostly from flowers with superior ovaries...
of the family Rosaceae
Rosaceae
Rosaceae are a medium-sized family of flowering plants, including about 2830 species in 95 genera. The name is derived from the type genus Rosa. Among the largest genera are Alchemilla , Sorbus , Crataegus , Cotoneaster , and Rubus...
such as peach
Peach
The peach tree is a deciduous tree growing to tall and 6 in. in diameter, belonging to the subfamily Prunoideae of the family Rosaceae. It bears an edible juicy fruit called a peach...
es, cherries
Cherry
The cherry is the fruit of many plants of the genus Prunus, and is a fleshy stone fruit. The cherry fruits of commerce are usually obtained from a limited number of species, including especially cultivars of the wild cherry, Prunus avium....
, plum
Plum
A plum or gage is a stone fruit tree in the genus Prunus, subgenus Prunus. The subgenus is distinguished from other subgenera in the shoots having a terminal bud and solitary side buds , the flowers in groups of one to five together on short stems, and the fruit having a groove running down one...
s, and apricot
Apricot
The apricot, Prunus armeniaca, is a species of Prunus, classified with the plum in the subgenus Prunus. The native range is somewhat uncertain due to its extensive prehistoric cultivation.- Description :...
s.
In nuts
Nut (fruit)
A nut is a hard-shelled fruit of some plants having an indehiscent seed. While a wide variety of dried seeds and fruits are called nuts in English, only a certain number of them are considered by biologists to be true nuts...
, it is the stony layer that surrounds the kernel of pecan
Pecan
The pecan , Carya illinoinensis, is a species of hickory, native to south-central North America, in Mexico from Coahuila south to Jalisco and Veracruz, in the United States from southern Iowa, Illinois, Missouri, and Indiana east to western Kentucky, southwestern Ohio, North Carolina, South...
s, walnut
Walnut
Juglans is a plant genus of the family Juglandaceae, the seeds of which are known as walnuts. They are deciduous trees, 10–40 meters tall , with pinnate leaves 200–900 millimetres long , with 5–25 leaflets; the shoots have chambered pith, a character shared with the wingnuts , but not the hickories...
s, etc., and that is removed prior to consumption.
In citrus, the endocarp is separated into sections, which are most commonly called segments. The juicy pulp filling the segments is usually referred to as juice vesicles
Juice vesicles
The juice vesicles of a citrus fruit are the membranous content of the fruit’s endocarp. The vesicles contain the juice of the fruit. The pulp is usually removed from the juice by filtering it out...
.
Anatomy of grass fruits
The grains of grasses are single-seed simple fruits wherein the pericarp (ovary wall) and seed coat are fused into one layer. This type of fruit is called a caryopsisCaryopsis
In botany, a caryopsis is a type of simple dry fruit — one that is monocarpelate and indehiscent and resembles an achene, except that in a caryopsis the pericarp is fused with the thin seed coat....
. Examples include cereal grains, such as wheat, barley, and rice.
See also
- Peel (fruit)Peel (fruit)Peel, also known as rind or skin, is the outer protective layer of a fruit or vegetable which could be peeled off. The rind is usually the botanical exocarp, but the term exocarp does also include the hard cases of nuts, which are not named peels since they are not peeled off by hand or peeler, but...
- HesperidiumHesperidiumA hesperidium is a modified fruit with a tough, leathery rind. The peel contains volatile oil glands in pits. The fleshy interior is composed of separate sections, called carpels, filled with fluid-filled vesicles that are actually specialized hair cells.The outer ovary wall becomes the thick...
the common citrusCitrusCitrus is a common term and genus of flowering plants in the rue family, Rutaceae. Citrus is believed to have originated in the part of Southeast Asia bordered by Northeastern India, Myanmar and the Yunnan province of China...
berryBerryThe botanical definition of a berry is a fleshy fruit produced from a single ovary. Grapes are an example. The berry is the most common type of fleshy fruit in which the entire ovary wall ripens into an edible pericarp. They may have one or more carpels with a thin covering and fleshy interiors....
. - GynoeciumGynoeciumGynoecium is most commonly used as a collective term for all carpels in a flower. A carpel is the ovule and seed producing reproductive organ in flowering plants. Carpels are derived from ovule-bearing leaves which evolved to form a closed structure containing the ovules...