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Elaiosome

Elaiosome

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Encyclopedia
Elaiosomes are fleshy structures that are attached to the 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...

s of many plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

 species. The elaiosome is rich in lipid
Lipid
Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...

s and protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

s, and may be variously shaped. Many plants have elaiosomes to attract ant
Ant
Ants are social insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than...

s, which take the seed to their nest and feed the elaiosome to their larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

e. After the larvae have consumed the elaiosome, the ants take the seed to their waste disposal area, which is rich in nutrients from the ant frass
Frass
Frass is the fine powdery material phytophagous insects pass as waste after digesting plant parts. It causes plants to excrete chitinase due to high chitin levels, it is a natural bloom stimulant, and has high nutrient levels. Frass is known to have abundant amoeba, beneficial bacteria, and fungi...

 and dead bodies, where the seeds germinate
Germination
Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...

. This type of seed dispersal is termed myrmecochory
Myrmecochory
Myrmecochory is seed dispersal by ants, an ecologically significant ant-plant interaction with worldwide distribution. Myrmecochorous plants produce seeds with elaiosomes, a term encompassing various external appendages or "food bodies" rich in lipids, amino acid, or other nutrients that are...

 from the Greek "ant" (myrmex) and "dispersal" (kore). This type of symbiotic
Symbiosis
Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...

 relationship appears to be mutualistic, more specifically dispersive mutualism according to Ricklefs, R.E. (2001), as the plant benefits because its seeds are dispersed to favorable germination sites, and also because it is planted (carried underground) by the ants.

Elaiosomes develop in various ways either from seed tissues (chalaza, funiculus, hilum, raphe-antiraphe) or from fruit tissues (exocarp, receptacle, flower tube, perigonium, style or spicule). The various origins and developmental pathways apparently all serve the same main function, i.e. attracting ants. Because elaiosomes are present in at least 11,000, but possibly up to 23,000 species of plants, elaiosomes are a dramatic example of convergent evolution
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...

 in flowering plants.

Elaioplast
Elaioplast
Elaioplasts are a type of leucoplast that is specialized for the storage of lipids in plants. Elaioplasts house oil body deposits as rounded plastoglobuli, which are essentially fat droplets....

s is another name for fat-producing cells (plastid
Plastid
Plastids are major organelles found in the cells of plants and algae. Plastids are the site of manufacture and storage of important chemical compounds used by the cell...

s).

Caruncle



The particular elaiosome in the spurge family Euphorbiaceae
Euphorbiaceae
Euphorbiaceae, the Spurge family are a large family of flowering plants with 300 genera and around 7,500 species. Most are herbs, but some, especially in the tropics, are also shrubs or trees. Some are succulent and resemble cacti....

is called caruncle (Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 caruncula "wart"). Seeds that have a caruncle are carunculate, seed that do not have a caruncle are ecarunculate.

List


A fully referenced current list of plants that have seeds with elaiosomes can be found in a reference.
  • Chelidonium majus (greater celandine)
  • Corydalis
    Corydalis
    Corydalis is a genus of about 470 species of annual and perennial herbaceous plants in the fumewort family , native to the temperate Northern Hemisphere and the high mountains of tropical eastern Africa...

  • Dicentra
    Dicentra
    Dicentra is a genus of 8 species of perennial herbaceous plants in the fumitory family, many with heart-shaped flowers, native to eastern Asia and North America.-Description:...

    (bleeding-heart, Dutchman's breeches)
  • Hyacinthus (hyacinth)
  • Myrtus (myrtle)
  • Sanguinaria canadensis (Bloodroot)
  • Trillium
    Trillium
    Trillium is a genus of about 40–50 species of spring ephemeral perennials, native to temperate regions of North America and Asia....

  • Viola (violet)

See also

  • Aril
    Aril
    An aril is any specialized outgrowth from the funiculus that covers or is attached to the seed. It is sometimes applied to any appendage or thickening of the seed coat in flowering plants, such as the edible parts of the mangosteen and pomegranate fruit, the mace of the nutmeg seed, or the...

  • Capitulum
    Capitulum
    The term Capitulum can refer to several things:*In botany, a type of flower head where the bracts are located under the basis, such as a daisy's*Also in botany, the top of a Sphagnum moss plant with compact clusters of young branches....

    , a similar appendage with similar purposes found in stick insect eggs.
  • Myrmecochory
    Myrmecochory
    Myrmecochory is seed dispersal by ants, an ecologically significant ant-plant interaction with worldwide distribution. Myrmecochorous plants produce seeds with elaiosomes, a term encompassing various external appendages or "food bodies" rich in lipids, amino acid, or other nutrients that are...