Endocarp in the context of "Simple fruit"

In botany, a drupe (or stone fruit) is a type of fruit in which an outer fleshy part (exocarp, or skin, and mesocarp, or flesh) surrounds a single shell (the pip (UK), pit (US), stone, or pyrena) of hardened endocarp with a seed (kernel) inside. Drupes do not split open to release the seed, i.e., they are indehiscent. These fruits usually develop from a single carpel, and mostly from flowers with superior ovaries (polypyrenous drupes are exceptions).

The definitive characteristic of a drupe is that the hard, woody (lignified) stone is derived from the ovary wall of the flower. In an aggregate fruit, which is composed of small, individual drupes (such as a raspberry), each individual is termed a drupelet, and may together form an aggregate fruit. Such fruits are often termed berries, although botanists use a different definition of berry. Other fleshy fruits may have a stony enclosure that comes from the seed coat surrounding the seed, but such fruits are not drupes.

A pyrena (/paɪˈriːnə/) or pyrene, commonly called a pit or stone, is the fruitstone within a drupe or drupelet produced by the ossification of the endocarp or lining of the fruit. It consists of a hard endocarp tissue surrounding one or more seeds (also called the "kernel"). The hardened endocarp which constitutes the pyrene provides a protective physical barrier around the seed, shielding it from pathogens and herbivory.

While many drupes are monopyrenous, containing only one pyrene, pome-type fruit with a hard, stony (rather than leathery) endocarp are typically polypyrenous drupes, containing multiple pyrenes.

An apricot kernel is the apricot seed located within the fruit endocarp, which forms a hard shell around the seed called the pyrena (stone or pit).

The kernel contains amygdalin, a poisonous compound, in concentrations that vary between cultivars. Together with the related synthetic compound laetrile, amygdalin has been marketed as an alternative cancer treatment. However, studies have found the compounds to be ineffective for treating cancer.

The juice vesicles, also known as citrus kernels (in aggregate, citrus pulp), of a citrus fruit are the membranous content of the fruit's endocarp. The vesicles contain the juice of the fruit and appear shiny and saclike. Vesicles come in two shapes: the superior and inferior, and these are distinct. Citrus fruits with more vesicles generally weigh more than those with fewer vesicles. Fruits with many segments, such as the grapefruit or pomelo, have more vesicles per segment than fruits with fewer segments, such as the kumquat and mandarin. Each vesicle in a segment in citrus fruits has approximately the same shape, size, and weight. About 5% of the weight of an average orange is made up of the membranes of the juice vesicles.

Juice vesicles of the endocarp contain the components that provide the aroma typically associated with citrus fruit. These components are also found in the flavedo oil sacs. The vesicles and their inner juices contain many vitamins and minerals as well as the taste and sweet acid fragrance.

Peel, also known as rind or skin, is the outer protective layer of a fruit or vegetable which can be peeled off. The rind is usually the botanical exocarp, but the term exocarp also includes the hard cases of nuts, which are not named peels since they are not peeled off by hand or peeler, but rather shells because of their hardness.

A fruit with a thick peel, such as a citrus fruit, is called a hesperidium. In hesperidia, the inner layer (also called albedo or, among non-botanists, pith) is peeled off together with the outer layer (called flavedo), and together they are called the peel. The flavedo and albedo, respectively, are the exocarp and the mesocarp. The juicy layer inside the peel (containing the seeds) is the endocarp.