achene

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Strawberry "seeds" seen up close, are clearly achenes.

An achene (also sometimes referred to as "akene" and occasionally "achenium" or "achenocarp") is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate (formed from one carpel) and indehiscent (they do not open at maturity). Achenes contain a single seed that nearly fills the pericarp, but does not adhere to it. In many species, what we think of as the "seed" is actually an achene, a fruit containing the seed.

Examples

cypsela of Cynara

Typical achenes are the fruits of buttercup, buckwheat, dandelion and cannabis.

The most familiar achenes are those of the strawberry, where the "seeds" are the achenes (technically the 'botanical' fruits), while what is eaten as the ('culinary') fruit is a so-called accessory fruit.

Fruits of sedges are sometimes considered achenes because they have a one-locule compound ovary. By the same definition, the common fruit type in the Family Asteraceae is also usually considered achene (although some scientists consider the asteraceous achene cypsela). For example, a sunflower "seed" in the husk is not a seed, but an achene. The white-gray husks are the walls of the fruit.

Variations

A winged achene, such as in maple, is called a samara. Some achenes tumble in the wind, similar to a tumbleweed; this type sometimes is called a "tumble fruit". An example is Anemone virginiana.

A rose also produces achenes, which are nestled inside the rose hips (each rose hip, or the fruit, holds a few achenes).

A grain is a type of fruit that closely resembles an achene, but differs in that the pericarp is fused to the thin seed coat in the grain.

A utricle is like an achene, but it has a compound ovary, rather than a simple one. In addition, its fruit ovary becomes bladdery or corky.

Gallery

Achenes on a dandelion, also known as dandelion clocks.

A microscopic view of a dandelion clock showing the pericarp and the achenes.

External links

• Botanical Glossary