achene

The fruits of buttercup, buckwheat, caraway, quinoa, amaranth, and cannabis are typical achenes.

The achenes of the strawberry are sometimes mistaken for seeds. The strawberry is an accessory fruit with an aggregate of achenes on its outer surface, and what is eaten is accessory tissue.

A rose produces an aggregate of achene fruits that are encompassed within an expanded hypanthium (aka floral tube), which is a structure where basal portions of the calyx, the corolla, and the stamens unite with the receptacle to form a cup-shaped tube.

A winged achene, as in maple, is called a samara.

Some achenes have accessory hair-like structures that cause them to tumble in the wind in a manner similar to a tumbleweed. This type sometimes is called a tumble fruit or diaspore. An example is Anemone virginiana.

A caryopsis or 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.

An utricle is like an achene, but the fruit is bladder-like or inflated.{{cite book |last1=Harris|first1=James G.|last2=Harris|first2=Melinda Woolf|date=2001 |title=Plant Identification Terminology: An Illustrated Glossary|edition=Second|url=https://archive.org/details/plantidentificat0000harr_f0f0|url-access=limited |location=Spring Lake, Utah|publisher=Spring Lake Publishing|via=Internet Archive Kahle/Austin Foundation |page=[https://archive.org/details/plantidentificat0000harr_f0f0/page/131/mode/2up 131] |isbn=0-9640221-6-8 |oclc=45951032}}

Fruits of sedges are sometimes considered achenes although their one-locule ovary is a compound ovary.

File:Cypsela Cynara.JPG]]

The fruit of the family Asteraceae is also so similar to an achene that it is often considered to be one, although it derives from a compound inferior ovary (with one locule). A special term for the Asteraceae fruit is cypsela (plural cypselae or cypselas). For example, the white-gray husks of a sunflower "seed" are the walls of the cypsela fruit.{{clarify|reason=a sunflower "seed" has a shell that splits into two, so how can it be an achene?|date=February 2016}} Many cypselas (e.g. dandelion) have modified calyx tissue called pappi attached that functions in biological dispersal of the seed.

File:Make a Wish by Vefobitseq.jpg|Cypselae on a dandelion "clock" (the matured capitulum) can disperse in the wind due to the hair-like calyx tissue above each ovary.

File:Dandelion Microscopic 1.jpg|A microscopic view of a dandelion "clock" showing the receptacle and the cypselas.

File:Acer buergerianum seeds.jpg|Samaras of Acer buergerianum are achenes with large wing-like structures.

File:Pulsatilla alpina fruit.JPG|The diaspore of Pulsatilla (family Ranunculaceae) disperses in the wind, either as single achenes or as the entire aggregate of achenes. The achenes have long hairy appendages that developed from the style of the flower.

File:Coreopsis tinctoria cultivar Uptick Cream and Red 12.JPG|Coreopsis tinctoria showing 4 stages of inflorescence, with two reddish-brown flower heads containing cypselas

File:Coreopsis tinctoria cultivar Uptick Cream and Red 13-achenes.jpg|Coreopsis tinctoria flower head containing cypselas forming as florets finish blooming

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• [https://web.archive.org/web/20070704063752/http://utc.usu.edu/factsheets/CarexFSF/glossary.htm Botanical Glossary]

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Category:Fruit morphology