Achene

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

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

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 (some term the asteraceous achene cypsela, however). A sunflower "seed" in the husk is not really a seed, but an achene. The white-gray husks are the walls of the fruit.