Examples:
– Fruits of buttercup, buckwheat, caraway, quinoa, amaranth, and cannabis are typical achenes.
– The strawberry has achenes mistaken for seeds, with an aggregate of achenes on its outer surface.
– A rose produces an aggregate of achene fruits within an expanded hypanthium.
– Maple has winged achenes called samaras.
– A caryopsis closely resembles an achene but has a fused pericarp to the thin seed coat.
Variations:
– Some achenes have hair-like structures causing them to tumble in the wind.
– A caryopsis differs from an achene as the pericarp is fused to the seed coat.
– An utricle is like an achene but is bladder-like or inflated.
– Fruits of sedges are sometimes considered achenes despite having a compound ovary.
– The fruit of Asteraceae, like the sunflower seed, is similar to an achene and is called a cypsela.
Gallery:
– Cypselae on a dandelion clock disperse in the wind due to hair-like calyx tissue.
– A microscopic view of a dandelion clock shows the receptacle and cypselas.
– Samaras of Acer buergerianum are achenes with large wing-like structures.
– Diaspores of Pulsatilla disperse in the wind as single achenes or aggregates with hairy appendages.
– Coreopsis tinctoria shows stages of inflorescence with reddish-brown flower heads containing cypselas.
References:
– Oxford English Dictionary defines achene.
– The New International Encyclopedia provides information on achenes.
– Plant Identification Terminology: An Illustrated Glossary by Harris and Woolf is a resource on achenes.
– Clarification is needed on cypsela fruit.
– Cypselas, like those of dandelions, have calyx tissue for seed dispersal.
External links:
– Wikimedia Commons has media related to Achenes.
An achene (/əˈkiːn/; from Ancient Greek ἀ (a) 'privative', and χαίνειν (khaínein) 'to gape'), also sometimes called 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 is called the "seed" is an achene, a fruit containing the seed. The seed-like appearance is owed to the hardening of the fruit wall (pericarp), which encloses the solitary seed so closely as to seem like a seed coat.