Fruit Terminology (Part 4)
Botany 115 Terminology
Fruit Terminology Part 4
D. Fleshy Fruits (Pericarp Is Fleshy At Maturity)
Note: In most fleshy fruits, the carpels are fused together and are not distinct as in dehiscent dry fruits. A notable exception is the hesperidium.
1. Berry: All or most of pericarp fleshy.
Although it is called a "vegetable," the tomato (Lycopersicon esculentum) is technically a botanical fruit referred to as a berry. Most of the interior tissue of a true berry is soft and fleshy.
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Pomegranate: An Unusual Berry
Pomegranate (Punica granatum), showing persistent calyx at the top of fruit. The calyx is cut away on right fruit to show the numerous stamens. The fruit is technically a leathery-skinned berry containing many seeds, each surrounded by a juicy, fleshy aril. The pomegranate tree is native to Africa and the Near East. Hebrews decorated their buildings with pomegranate motifs, and the beautiful, many-seeded fruits became associated with a symbol of fertility and abundance. In Asia, pomegranates were offered to wedding guests who threw them on the floor of the honeymoon suite, shattering the fruits and scattering the bright red seeds. This practice was believed to insure fertility and a large number of offspring for the newlyweds. The French word for a pomegranate is "grenade," which also refers to a hand-thrown bomb that scatters deadly metal fragments (shrapnel) instead of seeds.
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2. Pepo: Berry with hard, thick rind.
The watermelon is a good example of a pepo, a berry with a hard, thick rind. This is a triploid, seedless "yellow watermelon" (Citrullus lanatus var. lanatus). Although it is sold as "seedless," there are some seeds in the fleshy interior.
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Some species in the gourd family (Cucurbitaceae) produce a dehiscent capsule rather than a pepo. This wild cucumber fruit (Marah macrocarpus) splits open at one end exposing four chambers, each containing several large seeds.
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3. Hesperidium: Berry with a leathery rind.
The lemon (Citrus lemon) is a hesperidium, a berry with a leathery rind. The exocarp (peel) contains volatile oil glands (essential oils) in pits. The fleshy interior (endocarp) is composed of separate sections (carpels) filled with fluid-filled sacs (vesicles) that are actually specialized hair cells.
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Close-up view of the peel (exocarp) of a lemon (Citrus lemon) showing numerous pits containing volatile oil glands. Essential oils (terpenes and phenolic compounds) in the pits are responsible for the aroma given off when the peels are bruised or ground up. The fragrant perfume called bergamot comes from the fruit rinds of Citrus bergamia (C. aurantium ssp. bergamia). Essential oils in the pits of skins are extracted by maceration and modern hydraulic presses. The bitter chemical found in the mesocarp and parchment-like layers (partitions) surrounding the sections (carpels) of citrus fruits is limonin.
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Magnified longitudinal view of the endocarp of an orange (Citrus sinensis) showing several sections (carpels) filled with numerous fluid-filled "juice sacs." The two lower sections each contain a seed which is surrounded by the fleshy sacs. The sacs (vesicles) are actually swollen (plump), specialized hairs. According to K. Esau (Anatomy of Seed Plants, 1960), the juice sacs originate as multicellular hairs in which the interior of the enlarged distal part breaks down and fills with liquid. The juice sacs constitute the fleshy, edible pulp of an orange and are the source of the sweet juice. A bitter compound called limonin occurs in the mesocarp (rind) and membranous layers (partitions) surrounding the seed-bearing sections of grapefruits and other members of the citrus family (Rutaceae).
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4. Drupe: Seed enclosed within a stony endocarp (pit).
A 'California' peach (Prunus persica), a freestone peach grown in California's fertile Central Valley. The fruit is called a drupe because it is composed of three distinct layers: An outer skin or exocarp, a fleshy middle layer or mesocarp, and a hard, woody layer (endocarp) surrounding the seed. The lower pit (removed from another peach) has been sectioned to show the thick, woody layer or endocarp surrounding a single seed.
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5. Pome: Accessory fruit with thick hypanthium.
'Gala' apple, a cultivated variety of Malus domestica. The seed-bearing ovary (core) is surrounded by a thick, fleshy hypanthium that is not part of the pericarp. It derived from the fusion of the bases of the perianth segments (petals and sepals). Some references state that the hypanthium may also contain tissue from the receptacle. In the pome, the thickened, fleshy hypanthium is fused with the ovary wall or core. The outer skin of an apple is the multiseriate epidermis of the hypanthium surrounded by a waxy cuticle. Contrary to some references, it is not the exocarp of a ripened ovary. Depending on the variety, the skin contains red anthocyanin pigments. When you eat an apple, you are primarily biting into the hypanthium tissue. You may also consume some of the outer ovary (exocarp and mesocarp) that is fused with the thick hypanthium. Depending on how hungry you are, the inner ovary or seed-bearing core is usually not eaten, at least by most humans. Since the fruit contains tissue not derived from the pericarp, it is called an accessory fruit. This is the typical fruit of certain members of the rose family (Rosaceae), including apple, pear, quince and loquat.
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6. Aggregate Fruit: Many ovaries derived from a single flower.
Aggregate fruit of a hybrid strawberry (Fragaria x ananassa) showing the individual yellowish-brown, one-seeded achenes embedded in the red, fleshy receptacle. Although the one-seeded achenes represent separate ripened ovaries, each strawberry is produced from a single white flower bearing many stamens.
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Flower and aggregate fruit of thimbleberry (Rubus parviflorus), a native shrub in the mountains of the western United States. Although the tiny, one-seeded drupelets represent separate ripened ovaries, each aggregate cluster of fleshy drupelets developed from a single white flower.
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7. Multiple Fruit: Many ovaries derived from many individual flowers.
Black mulberry (Morus nigra), a dioecious tree native to western Asia. The bumpy surface of the fruit is due to many tightly-packed, seed-bearing ovaries (drupelets), each with separate styles that appear like black hairs. It is technically a multiple fruit (called a syncarp) composed of a cluster of drupelets superficially resembling a blackberry; however, unlike a blackberry, each drupelet arises from a separate, minute, unisexual (female) flower. Each monocarpellate pistil (also referred as a gynoecium) consists of a forked stigma, a short style and a spherical ovary. In the aggregate fruit of a blackberry, all the drupelets of the cluster (syncarp) come from a single flower. Seedless, parthenocarpic mulberry fruits are produced without pollination.
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