Achene
Encyclopedia
An achene is a type of simple dry fruit
produced by many species of flowering plant
s. 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. The seed-like appearance arises from the fact that the wall of the seed-vessel hardens and encloses the solitary seed so closely as to seem like an outer coat.
Typical achenes are the fruits of buttercup, buckwheat
, and cannabis
.
The achenes of the strawberry
are familiar, where the "seeds" are achenes. Technically, the strawberry is an aggregate fruit with an aggregate of achenes, and what is eaten is accessory tissue, so this is an aggregate accessory fruit
.
A rose
also produces achenes. Each fruit, called a rose hip, holds a few achenes.
, is called a samara
.
Some achenes have accessory hair-like structures that cause them to tumble in the wind, 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 it has a compound ovary, sometimes with several seeds. In addition, the ovary of the fruit becomes bladder-like or corky.
Fruits of sedge
s are sometimes considered achenes although their one-locule ovary is actually a compound ovary
.
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. Many cypselas (e.g. dandelion) have calyx tissue attached that functions in biological dispersal
of the seed.
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
produced by many species of flowering plant
Flowering plant
The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...
s. Achenes are monocarpellate (formed from one carpel) and indehiscent (they do not open at maturity). Achenes contain a single seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
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. The seed-like appearance arises from the fact that the wall of the seed-vessel hardens and encloses the solitary seed so closely as to seem like an outer coat.
Examples
Buckwheat
Buckwheat refers to a variety of plants in the dicot family Polygonaceae: the Eurasian genus Fagopyrum, the North American genus Eriogonum, and the Northern Hemisphere genus Fallopia. Either of the latter two may be referred to as "wild buckwheat"...
, and cannabis
Cannabis
Cannabis is a genus of flowering plants that includes three putative species, Cannabis sativa, Cannabis indica, and Cannabis ruderalis. These three taxa are indigenous to Central Asia, and South Asia. Cannabis has long been used for fibre , for seed and seed oils, for medicinal purposes, and as a...
.
The achenes of the strawberry
Strawberry
Fragaria is a genus of flowering plants in the rose family, Rosaceae, commonly known as strawberries for their edible fruits. Although it is commonly thought that strawberries get their name from straw being used as a mulch in cultivating the plants, the etymology of the word is uncertain. There...
are familiar, where the "seeds" are achenes. Technically, the strawberry is an aggregate fruit with an aggregate of achenes, and what is eaten is accessory tissue, so this is an aggregate accessory fruit
Accessory fruit
An accessory fruit is a fruit in which some of the flesh is derived not from the ovary but from some adjacent tissue exterior to the carpel. Examples of accessory tissue are the receptacle of strawberries, figs, or mulberries, and the calyx of Gaultheria procumbens or Syzygium jambos...
.
A rose
Rose
A rose is a woody perennial of the genus Rosa, within the family Rosaceae. There are over 100 species. They form a group of erect shrubs, and climbing or trailing plants, with stems that are often armed with sharp prickles. Flowers are large and showy, in colours ranging from white through yellows...
also produces achenes. Each fruit, called a rose hip, holds a few achenes.
Variations
A winged achene, such as in mapleMaple
Acer is a genus of trees or shrubs commonly known as maple.Maples are variously classified in a family of their own, the Aceraceae, or together with the Hippocastanaceae included in the family Sapindaceae. Modern classifications, including the Angiosperm Phylogeny Group system, favour inclusion in...
, is called a samara
Samara (fruit)
A samara is a type of fruit in which a flattened wing of fibrous, papery tissue develops from the ovary wall. A samara is a simple dry fruit and indehiscent . It is a winged achene...
.
Some achenes have accessory hair-like structures that cause them to tumble in the wind, similar to a tumbleweed
Tumbleweed
A tumbleweed is the above-ground part of a plant that, once mature and dry, disengages from the root and tumbles away in the wind. Usually, the tumbleweed is the entire plant apart from the roots, but in a few species it is a flower cluster. The tumbleweed habit is most common in steppe and desert...
; this type sometimes is called a "tumble fruit" or diaspore
Diaspore (botany)
In botany, a diaspore is a plant dispersal unit consisting of a seed or spore plus any additional tissues that assist dispersal. In some seed plants, the diaspore is a seed and fruit together, or a seed and elaiosome. In a few seed plants, the diaspore is most or all of the plant, known as a...
. An example is Anemone virginiana
Anemone virginiana
Anemone virginiana is an upright growing herbaceous plant species in the genus Anemone and family Ranunculaceae. Plants grow 30 to 80 cm tall, flowering early summer but often found flowering till late summer, the flowers are white or greenish-white...
.
A caryopsis
Caryopsis
In botany, a caryopsis is a type of simple dry fruit — one that is monocarpelate and indehiscent and resembles an achene, except that in a caryopsis the pericarp is fused with the thin seed coat....
or grain
GRAIN
GRAIN is a small international non-profit organisation that works to support small farmers and social movements in their struggles for community-controlled and biodiversity-based food systems. Our support takes the form of independent research and analysis, networking at local, regional and...
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 it has a compound ovary, sometimes with several seeds. In addition, the ovary of the fruit becomes bladder-like or corky.
Fruits of sedge
Cyperaceae
Cyperaceae are a family of monocotyledonous graminoid flowering plants known as sedges, which superficially resemble grasses or rushes. The family is large, with some 5,500 species described in about 109 genera. These species are widely distributed, with the centers of diversity for the group...
s are sometimes considered achenes although their one-locule ovary is actually a compound ovary
Ovary
The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in anatomically female individuals are analogous to testes in anatomically male individuals, in that they are both gonads and endocrine glands.-Human anatomy:Ovaries...
.
The fruit of the family Asteraceae
Asteraceae
The Asteraceae or Compositae , is an exceedingly large and widespread family of vascular plants. The group has more than 22,750 currently accepted species, spread across 1620 genera and 12 subfamilies...
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
Sunflower
Sunflower is an annual plant native to the Americas. It possesses a large inflorescence . The sunflower got its name from its huge, fiery blooms, whose shape and image is often used to depict the sun. The sunflower has a rough, hairy stem, broad, coarsely toothed, rough leaves and circular heads...
"seed" are the walls of the cypsela fruit. Many cypselas (e.g. dandelion) have calyx tissue attached that functions in biological dispersal
Biological dispersal
Biological dispersal refers to species movement away from an existing population or away from the parent organism. Through simply moving from one habitat patch to another, the dispersal of an individual has consequences not only for individual fitness, but also for population dynamics, population...
of the seed.