Elaiosomes ( ''élaion'' "oil" + ''sóma'' "body") are fleshy structures that are attached to the
seed
In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be Sowing, sown, which may include seed and husk or tuber. Seeds ...
s of many
plant
Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...
species. The elaiosome is rich in
lipid
Lipids are a broad group of organic compounds which include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include storing ...
s and
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
s, and may be variously shaped. Many plants have elaiosomes that attract
ant
Ants are Eusociality, eusocial insects of the Family (biology), family Formicidae and, along with the related wasps and bees, belong to the Taxonomy (biology), order Hymenoptera. Ants evolved from Vespoidea, vespoid wasp ancestors in the Cre ...
s, which take the seed to their nest and feed the elaiosome to their
larva
A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...
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 and dead bodies, where the seeds
germinate
Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an flowering plant, angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the sp ...
. This type of seed dispersal is termed
myrmecochory
Myrmecochory ( (sometimes myrmechory); from ("ant") and ''khoreíā'' ("circular dance") is seed dispersal by ants, an ecologically significant Myrmecophily, ant–plant Biological interaction, interaction with worldwide distribution. Most ...
from the Greek "ant" (myrmex) and "circular dance" (khoreíā). This type of
symbiotic
Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biolo ...
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 is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last comm ...
in flowering plants.
Caruncle
The particular elaiosome in the spurge family ''
Euphorbiaceae
Euphorbiaceae (), the spurge family, is a large family of flowering plants. In English, they are also commonly called euphorbias, which is also the name of Euphorbia, the type genus of the family. Most spurges, such as ''Euphorbia paralias'', ar ...
'' is called caruncle (
Latin
Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...
''caruncula'' "wart"). Seeds that have caruncles are ''carunculate''; seeds that do not have caruncles are ''ecarunculate''.
List
A fully referenced current list of plants that have seeds with elaiosomes can be found in Lengyel ''et al.'' (2010).
*''
Chelidonium majus'' (greater celandine)
*''
Claytonia virginica
''Claytonia virginica'', the Virginia springbeauty, eastern spring beauty, grass-flower narrowleaf springbeauty or fairy spud, is an herbaceous perennial plant in the family Montiaceae. Its native range is eastern North America. Its scientific na ...
''
*''
Cnidoscolus urens''
*''
Corydalis
''Corydalis'' (from Greek ''korydalís'' " crested lark") is a genus of about 540 species of annual and perennial herbaceous plants in the family Papaveraceae, native to the temperate Northern Hemisphere and the high mountains of tropical ...
''
*''
Dicentra'' (bleeding-heart, Dutchman's breeches)
*''
Hyacinthus'' (hyacinth)
*''
Myrtus'' (myrtle)
*''
Ricinus communis'' (castor oil plant)
*''
Sanguinaria canadensis
''Sanguinaria canadensis'', bloodroot, is a perennial, herbaceous flowering plant native to eastern North America. It is the only species in the genus ''Sanguinaria'', included in the poppy family Papaveraceae, and is most closely related to ' ...
'' (Bloodroot)
*''
Trillium
''Trillium'' (trillium, wakerobin, toadshade, tri flower, birthroot, birthwort, and sometimes "wood lily") is a genus of about fifty flowering plant species in the family Melanthiaceae. ''Trillium'' species are native to temperate regions of No ...
''
*''
Viola
The viola ( , () ) is a string instrument of the violin family, and is usually bowed when played. Violas are slightly larger than violins, and have a lower and deeper sound. Since the 18th century, it has been the middle or alto voice of the ...
'' (violet)
See also
*
Aril
An aril (), also called arillus, is a specialized outgrowth from a seed that partly or completely covers the seed. An arillode, or false aril, is sometimes distinguished: whereas an aril grows from the attachment point of the seed to the ova ...
*
Capitulum, a similar appendage with similar purposes found in
stick insect
The Phasmatodea (also known as Phasmida or Phasmatoptera) are an order of insects whose members are variously known as stick insects, stick bugs, walkingsticks, stick animals, or bug sticks. They are also occasionally referred to as Devil's da ...
eggs.
*
Myrmecochory
Myrmecochory ( (sometimes myrmechory); from ("ant") and ''khoreíā'' ("circular dance") is seed dispersal by ants, an ecologically significant Myrmecophily, ant–plant Biological interaction, interaction with worldwide distribution. Most ...
References
External links
*http://waynesword.palomar.edu/plaug99.htm#antdispersal {{Webarchive, url=https://web.archive.org/web/20151110064020/http://waynesword.palomar.edu/plaug99.htm#antdispersal , date=2015-11-10
Fruit morphology
Insect ecology