An aggregate fruit or etaerio or etario is a fruit that develops from the merger of several ovaries that were separate in a single flower. In contrast, a simple fruit develops from one ovary. In languages other than English, the meanings of aggregate and multiple fruit are reversed, so that aggregate fruits merge several flowers. The differences in meaning are due to a reversal in the terminology by John Lindley, which has been followed by most English-language authors.
Not all flowers with multiple ovaries form aggregate fruit; the ovaries of some flowers do not become tightly joined together to make a larger fruit. Aggregate fruits may also be accessory fruits, in which parts of the flower other than the ovary become fleshy and form part of the fruit.
The individual parts of an aggregate fruit come in many forms. Common examples are:
- Multiple fruit, a structure formed from the ovaries of several flowers, that can resemble an aggregate fruit
- Compound fruit, a term sometimes used when it is not clear whether a fruit is an aggregate fruit, a multiple fruit, or a simple fruit formed from a compound ovary
- Carpel, the "building blocks" of the ovary
- Hickey, M.; King, C. (2001). The Cambridge Illustrated Glossary of Botanical Terms. translated by. Cambridge University Press.
- Spjut, R.; Thieret, J. (1989). "Confusion between multiple and aggregate fruits". The Botanical Review 55 (1): 53–72. doi:10.1007/bf02868781.
- Beentje, H.; Williamson, J. (2010). The Kew Plant Glossary: an Illustrated Dictionary of Plant Terms. Royal Botanic Gardens, Kew: Kew Publishing.
- Janick, J.; Paull, R.E. (2008). The Encyclopedia of Fruit and Nuts. CABI. ISBN 9780851996387.