Arils

The red juicy bits found inside a pomegranate are called arils. Arils are a type of accessory fruit, or false fruit.

Pomegranate arils (Kate Russell)

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True fruits and false fruits

Fruit is the tissue that surrounds the seeds of angiosperms (flowering plants). Fruit is made from a plant’s ovary. Except when it isn’t. In some cases, a fruit develops from both the ovary and nearby tissue. These tissues can be either the perianth (flower whorls) or the hypanthium (the flower base). When this occurs, the part we eat is called an accessory fruit, or false fruit. Common accessory fruits include figs, mulberries, pineapples, and strawberries. Arils are specialized versions of these false fruits.


Aril anatomy

Arils are outgrowths that cover seeds partially or fully, which may or may not turn in to an edible fruit. This outgrowth originates where the seed attaches to the ovary, at the hilum. Along with pomegranates, the spice known as mace is an aril. Mace is a striking red aril that surrounds a nutmeg.

A nutmeg aril is used as a spice called mace (Ramesh NG) CC BY-SA 2.0

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A slightly different version, called an arillode or false aril, emerges from a different location on the seed coat. Lychee, for example, grows partly from the hilum and partly from the integument or coating of the seed. The same is true for soapnuts. And yew creates a cup-shaped aril fruit, rather than a traditional cone.

The edible white part of lychee is an arillode or false aril. (Peggy Greb, Public Domain)

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Like other fruits, the aril serves as an attractant to herbivores. As birds, animals, and people eat these fruits, the seeds are spread farther and wides, improving the odds of continuing that particular line of genetic information.


Now you know.