Elaiosomes (Ancient Greek:ἔλαιονélaion "oil" +σόμαsóma "body") are fleshy structures that are attached to theseeds of manyplant species. The elaiosome is rich inlipids andproteins, and may be variously shaped. Many plants have elaiosomes that attractants, which take the seed to their nest and feed the elaiosome to theirlarvae. After the larvae have consumed the elaiosome, the ants take the seed to their waste disposal area, which is rich in nutrients from the antfrass and dead bodies, where the seedsgerminate. This type of seed dispersal is termedmyrmecochory from the Greek "ant" (myrmex) and "circular dance" (khoreíā). This type ofsymbiotic relationship appears to bemutualistic, 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).[1] 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 ofconvergent evolution in flowering plants.[2]
The particular elaiosome in the spurge familyEuphorbiaceae is calledcaruncle (Latincaruncula "wart"). Seeds that have caruncles arecarunculate; seeds that do not have caruncles areecarunculate.
A fully referenced current list of plants that have seeds with elaiosomes can be found in Lengyelet al. (2010).[2]