noun, plural: achenes
The fruits produced by angiosperms (flowering plants) may be grouped in many ways. One of which is to categorize fruits as either fleshy or dry. A fleshy fruit is one in which part or all of the pericarp is fleshy at maturity. These are exemplified by berries and drupes. A dry fruit is, in contrast, not fleshy and the pericarp layers (i.e. epicarp, mesocarp, and endocarp) are hardly distinguishable. Dry fruits may further be grouped as dehiscent, indehiscent, or schizocarpic. A dehiscent fruit is one that splits open when ripe. An indehiscent fruit does not split open even when the seeds reach maturity. A schizocarpic fruit is intermediate by being indehiscent and capsular at the same time.
An achene is an indehiscent, dry fruit. It is found in many species of angiosperms. The fruit develops from a single carpelate (monocarpelate) and therefore contains a single seed. The seed nearly fills the pericarp but it does not adhere to it but only at one point of the pericarp. Examples of achenes are certain simple fruits such as rose hip, buckwheat, cannabis, caraway, and buttercup.
The strawberry fruit is a special type of fruit. It is an aggregate of achenes. The strawberry achenes, which are thought of as seeds, are actually the fruits in a cluster whereas the red, juicy, edible flesh with achenes is an accessory tissue. Because of these characteristics, the strawberry fruit is also typified as an aggregate fruit or as an accessory fruit.
Word origin: Greek ἀ- (“without”) + khaínō (“to gape”)