Myrmecophyte
Encyclopedia
Myrmecophyte is a plant
that lives in a mutualistic association with a colony of ants. There are over 100 different genera of myrmecophytes. These plants possess structural adaptations that provide ants with food and/or shelter. These specialized structures include domatia, food bodies, and extrafloral nectaries. In exchange for food and shelter, ants aid the myrmecophyte in pollination
, seed dispersal
, gathering of essential nutrients, and/or defense. Specifically, domatia adapted to ants may be called myrmecodomatia.
genus of plants. All species of this genus provide food for ants in various forms, but only the obligate species produce domatia. Some of the most common species of myrmecophytic Macaranga interact with ants in the Crematogaster
genus. C. borneensis have been found to be completely dependent on its partner plant, not being able to survive without the provided nesting spaces and food bodies. In laboratory tests, the worker ants did not survive away from the plants, and in their natural habitat they were never found anywhere else.
has not occurred. For example, Old World
legumes that were introduced to North America
can be protected by ants that originated from a different region.
are internal plant structures that appear to be specifically adapted for habitation by ants. These cavities are found primarily in the stems
, leaves
, and spines of plants. Many different genera of plants offer domatia. Plants of the Acacia
genus have some of the most widely recognized forms of domatia and offer some of the best examples of ant-plant obligate mutualism. Different species of Acacia provide a variety of resources needed for their codependent counterparts. One of these resources is the need for shelter. Acacia have enlarged thorns on their stems that are excavated by ants for use as housing structures. Since the tree contains their nest, these aggressive ants react strongly to any disturbance of the tree, providing the myrmecophyte with defense from grazing herbivores and encroaching vine
s.
Domatia can also be found within the tubers of certain plants. Tubers form when the hypocotyl
s of a seedling swells to form a hollow, chambered structure that can become inhabited by ants. The Rubiaceae
family of plants contains the most commonly known tuberous myrmecophyte, Myrmecodia
, literally meaning “ant-house”.
structures contain a variety of nutrients that are removed and consumed by foragers. Food bodies are identified by the main nutrient
they contain and by the genus of plant producing them. Beltian bodies are found on the leaflet tips of Acacia
plants and have relatively high protein
content . Beccarian bodies are found on young leaves of the Macaranga
genus and are especially rich in lipids. Lipids are also the main nutrient found in Pearl bodies, found on the leaves and stems of Ochroma plants. Most ant inhabitantsof Cecropia
plants harvest the last type of food body, as their primary food source. Remarkably these Müllerian bodies, found on the stalk of the leaf, are primarily glycogen
. Glycogen is the principal storage carbohydrate
found in animal
s and is extremely rare in plants.
structures of plants. They occur in many different plant species around the world and are most commonly associated with vegetative structures that normally do not have nectaries, such as leaves
, stems
, and twig
s. These secreting structures are often non-exclusive in that nectar can be taken by a variety of animals; however, in some obligate myrmecophyte plants such as Acacia collinsii
, extrafloral nectar is modified to be attractive only to the ant partners in the symbiosis. The nectar thus provided feeds ants, which in turn protect these myrmecophytes from herbivorous activity. A species of deciduous tree that displays extrafloral nectaries, Catalpa speciosa, shows a decreased loss of leaf tissue on branches protected by ants, and an increase in number of seeds produced.
relatives, ants rarely pollinate plants. Various assumptions have been made as to why ants are poor pollinators, although none have been verified: a) ants do not fly limiting their transport of pollen far enough to effect cross-pollination, b) ants do not systematically forage like bees do, and c) ants are not hairy, and clean themselves too frequently to allow pollen to be carried to other plants. In most cases of ant pollination, the ants are one of multiple pollinators; meaning that the plants are not completely dependent on ants for pollination. However the orchid, Leporella fimbriata can only be pollinated by its winged male ant partner.
, literally translated as “ant-dispersal,” is the collection and dispersal of seeds
by ants. Ants disperse more than 30% of the spring-flowering herbaceous plants in eastern North America
. Both the plant and the ant benefit in this scenario. The ants are provided with an elaiosome
, a detachable food body found on the surface of the seed. Elaiosomes have diverse compositions, usually high in lipids and fatty acids, but also containing amino acids, sugars, and protein
. The ants remove the elaiosome once the seed has been transported to the colony
. As a result, the seeds are safely placed in nutrient-rich substrate protected from predators, benefiting the plant with optimum establishment conditions for its seed.
, meaning “ant-fed,” is the ability of plants to absorb nutrients from debris piles left by ant nests. The tropical tree Cecropia
peltata obtains 98% of its nitrogen from the waste deposited by its ant counterparts.
, for example, is thoroughly guarded by its obligate ant partner, Pseudomyrmex ferruginea
. A single colony of P. ferruginea may contain more than 30,000 ants, and can tend multiple Acacia trees. The soldier ants are extremely aggressive, patrolling the trees twenty-four hours a day. Any disturbance to the tree alerts ants, who then recruit more workers from inside the horn domatia. These ants defend the Acacia by biting, violently stinging, and pruning
any trespassers. The ants keep the plant free from other insects and vertebrate herbivores, but also from invading fungi and other plants.
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...
that lives in a mutualistic association with a colony of ants. There are over 100 different genera of myrmecophytes. These plants possess structural adaptations that provide ants with food and/or shelter. These specialized structures include domatia, food bodies, and extrafloral nectaries. In exchange for food and shelter, ants aid the myrmecophyte in pollination
Pollination
Pollination is the process by which pollen is transferred in plants, thereby enabling fertilisation and sexual reproduction. Pollen grains transport the male gametes to where the female gamete are contained within the carpel; in gymnosperms the pollen is directly applied to the ovule itself...
, seed dispersal
Seed dispersal
Seed dispersal is the movement or transport of seeds away from the parent plant. Plants have limited mobility and consequently rely upon a variety of dispersal vectors to transport their propagules, including both abiotic and biotic vectors. Seeds can be dispersed away from the parent plant...
, gathering of essential nutrients, and/or defense. Specifically, domatia adapted to ants may be called myrmecodomatia.
Mutualism
Myrmecophytes share a mutualistic relationship with ants, benefiting both the plants and ants. This association may be either facultative or obligate.Obligate mutualism
In obligate mutualisms, both of the organisms involved are interdependent; they cannot survive on their own. An example of this type of mutualism can be found in the MacarangaMacaranga
Macaranga is a large genus of Old World tropical trees of the family Euphorbiaceae and the only genus in the subtribe Macaranginae. Native to Africa, Australasia, Asia and the South Pacific, the genus comprises over 300 different species. These plants are noted for being recolonizers...
genus of plants. All species of this genus provide food for ants in various forms, but only the obligate species produce domatia. Some of the most common species of myrmecophytic Macaranga interact with ants in the Crematogaster
Crematogaster
Crematogaster is an ecologically diverse genus of ants found worldwide, which are characterised by a distinctive heart-shaped gaster , which gives one of their common names, Valentine Ant. It is the only genus of the tribus Crematogastrini. Most of species are arboreal...
genus. C. borneensis have been found to be completely dependent on its partner plant, not being able to survive without the provided nesting spaces and food bodies. In laboratory tests, the worker ants did not survive away from the plants, and in their natural habitat they were never found anywhere else.
Facultative mutualism
Facultative mutualism is a type of relationship where the survival of both parties (plant and ants, in this instance), is not dependent upon the interaction. Both organisms can survive without the other species. Facultative mutualisms most often occur in plants that have extrafloral nectaries but no other specialized structures for the ants. These non-exclusive nectaries allow a variety of animal species to interact with the plant. Facultative relationships can also develop between non-native plant and ant species, where co-evolutionCo-evolution
In biology, coevolution is "the change of a biological object triggered by the change of a related object." Coevolution can occur at many biological levels: it can be as microscopic as correlated mutations between amino acids in a protein, or as macroscopic as covarying traits between different...
has not occurred. For example, Old World
Old World
The Old World consists of those parts of the world known to classical antiquity and the European Middle Ages. It is used in the context of, and contrast with, the "New World" ....
legumes that were introduced to North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
can be protected by ants that originated from a different region.
Structural adaptations of myrmecophytes
Domatia
DomatiaDomatia
Domatia are tiny chambers produced by plants that house arthropods.Domatia differ from galls in that they are produced by the plant rather than being induced by their inhabitants...
are internal plant structures that appear to be specifically adapted for habitation by ants. These cavities are found primarily in the stems
Plant stem
A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , conifer cones, roots, other stems etc. The internodes distance one node from another...
, leaves
Leaves
-History:Vocalist Arnar Gudjonsson was formerly the guitarist with Mower, and he was joined by Hallur Hallsson , Arnar Ólafsson , Bjarni Grímsson , and Andri Ásgrímsson . Late in 2001 they played with Emiliana Torrini and drew early praise from the New York Times...
, and spines of plants. Many different genera of plants offer domatia. Plants of the Acacia
Acacia
Acacia is a genus of shrubs and trees belonging to the subfamily Mimosoideae of the family Fabaceae, first described in Africa by the Swedish botanist Carl Linnaeus in 1773. Many non-Australian species tend to be thorny, whereas the majority of Australian acacias are not...
genus have some of the most widely recognized forms of domatia and offer some of the best examples of ant-plant obligate mutualism. Different species of Acacia provide a variety of resources needed for their codependent counterparts. One of these resources is the need for shelter. Acacia have enlarged thorns on their stems that are excavated by ants for use as housing structures. Since the tree contains their nest, these aggressive ants react strongly to any disturbance of the tree, providing the myrmecophyte with defense from grazing herbivores and encroaching vine
Vine
A vine in the narrowest sense is the grapevine , but more generally it can refer to any plant with a growth habit of trailing or scandent, that is to say climbing, stems or runners...
s.
Domatia can also be found within the tubers of certain plants. Tubers form when the hypocotyl
Hypocotyl
The hypocotyl is the stem of a germinating seedling, found below the cotyledons and above the radicle .-Dicots:...
s of a seedling swells to form a hollow, chambered structure that can become inhabited by ants. The Rubiaceae
Rubiaceae
The Rubiaceae is a family of flowering plants, variously called the coffee family, madder family, or bedstraw family. The group contains many commonly known plants, including the economically important coffee , quinine , and gambier , and the horticulturally valuable madder , west indian jasmine ,...
family of plants contains the most commonly known tuberous myrmecophyte, Myrmecodia
Myrmecodia
Myrmecodia is a genus of epiphytic myrmecophytes native to Southeast Asia and large islands extending south to Queensland in Australia. Myrmecodia plants grow in tree branches and on trunks. In nature, Myrmecodia tubers often grow hanging downward on bare branches without significant amounts of...
, literally meaning “ant-house”.
Food bodies
Some plants produce food bodies for use by other organisms. These small epidermalEpidermis (botany)
The epidermis is a single-layered group of cells that covers plants' leaves, flowers, roots and stems. It forms a boundary between the plant and the external environment. The epidermis serves several functions, it protects against water loss, regulates gas exchange, secretes metabolic compounds,...
structures contain a variety of nutrients that are removed and consumed by foragers. Food bodies are identified by the main nutrient
Nutrient
A nutrient is a chemical that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment. They are used to build and repair tissues, regulate body processes and are converted to and used as energy...
they contain and by the genus of plant producing them. Beltian bodies are found on the leaflet tips of Acacia
Acacia
Acacia is a genus of shrubs and trees belonging to the subfamily Mimosoideae of the family Fabaceae, first described in Africa by the Swedish botanist Carl Linnaeus in 1773. Many non-Australian species tend to be thorny, whereas the majority of Australian acacias are not...
plants and have relatively high 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...
content . Beccarian bodies are found on young leaves of the Macaranga
Macaranga
Macaranga is a large genus of Old World tropical trees of the family Euphorbiaceae and the only genus in the subtribe Macaranginae. Native to Africa, Australasia, Asia and the South Pacific, the genus comprises over 300 different species. These plants are noted for being recolonizers...
genus and are especially rich in lipids. Lipids are also the main nutrient found in Pearl bodies, found on the leaves and stems of Ochroma plants. Most ant inhabitantsof Cecropia
Cecropia
Cecropia is a Neotropical genus presently consisting of sixty-one recognized species with a highly distinctive lineage of dioecious trees....
plants harvest the last type of food body, as their primary food source. Remarkably these Müllerian bodies, found on the stalk of the leaf, are primarily glycogen
Glycogen
Glycogen is a molecule that serves as the secondary long-term energy storage in animal and fungal cells, with the primary energy stores being held in adipose tissue...
. Glycogen is the principal storage carbohydrate
Carbohydrate
A carbohydrate is an organic compound with the empirical formula ; that is, consists only of carbon, hydrogen, and oxygen, with a hydrogen:oxygen atom ratio of 2:1 . However, there are exceptions to this. One common example would be deoxyribose, a component of DNA, which has the empirical...
found in animal
Animal
Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...
s and is extremely rare in plants.
| Beltian bodies | Protein | Acacia | Leaflet tips |
| Beccarian bodies | Lipids | Macaranga | Young leaves |
| Pearl bodies | Lipids | Ochroma | Leaves and stems |
| Müllerian bodies | Glycogen | Cecropia | Petiole of the leaf |
Extrafloral nectaries
Extrafloral nectaries are sugar-producing glands found outside the flowerFlower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
structures of plants. They occur in many different plant species around the world and are most commonly associated with vegetative structures that normally do not have nectaries, such as leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
, stems
Plant stem
A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , conifer cones, roots, other stems etc. The internodes distance one node from another...
, and twig
Twig
A twig is a small thin terminal branch of a woody plant. Twigs are critically important in identification of trees, shrubs and vines, especially in wintertime. The buds on the twig are an important diagnostic characteristic, as are the abscission scars where the leaves have fallen away...
s. These secreting structures are often non-exclusive in that nectar can be taken by a variety of animals; however, in some obligate myrmecophyte plants such as Acacia collinsii
Acacia collinsii
Acacia collinsii is a species of flowering plant. It grows in secondary succession in seasonally dry ecosystems in southern Central America, where it exhibits a symbiotic relationship with several species of ant...
, extrafloral nectar is modified to be attractive only to the ant partners in the symbiosis. The nectar thus provided feeds ants, which in turn protect these myrmecophytes from herbivorous activity. A species of deciduous tree that displays extrafloral nectaries, Catalpa speciosa, shows a decreased loss of leaf tissue on branches protected by ants, and an increase in number of seeds produced.
Ants as pollinators
Unlike their beeBee
Bees are flying insects closely related to wasps and ants, and are known for their role in pollination and for producing honey and beeswax. Bees are a monophyletic lineage within the superfamily Apoidea, presently classified by the unranked taxon name Anthophila...
relatives, ants rarely pollinate plants. Various assumptions have been made as to why ants are poor pollinators, although none have been verified: a) ants do not fly limiting their transport of pollen far enough to effect cross-pollination, b) ants do not systematically forage like bees do, and c) ants are not hairy, and clean themselves too frequently to allow pollen to be carried to other plants. In most cases of ant pollination, the ants are one of multiple pollinators; meaning that the plants are not completely dependent on ants for pollination. However the orchid, Leporella fimbriata can only be pollinated by its winged male ant partner.
Ants and seed dispersal
MyrmecochoryMyrmecochory
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...
, literally translated as “ant-dispersal,” is the collection and dispersal of seeds
SEEDS
SEEDS is a voluntary organisation registered under the Societies Act of India....
by ants. Ants disperse more than 30% of the spring-flowering herbaceous plants in eastern North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. Both the plant and the ant benefit in this scenario. The ants are provided with an elaiosome
Elaiosome
Elaiosomes are fleshy structures that are attached to the seeds of many plant species. The elaiosome is rich in lipids and proteins, and may be variously shaped. Many plants have elaiosomes to attract ants, which take the seed to their nest and feed the elaiosome to their larvae...
, a detachable food body found on the surface of the seed. Elaiosomes have diverse compositions, usually high in lipids and fatty acids, but also containing amino acids, sugars, 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...
. The ants remove the elaiosome once the seed has been transported to the colony
Ant colony
An ant colony is an underground lair where ants live, eat and mate. Colonies consist of a series of underground chambers, connected to each other and the surface of the earth by small tunnels. There are rooms for nurseries, food storage, and mating...
. As a result, the seeds are safely placed in nutrient-rich substrate protected from predators, benefiting the plant with optimum establishment conditions for its seed.
Ants feeding plants
MyrmecotrophyMyrmecotrophy
Myrmecotrophy is the ability of plants to obtain nutrients from ants, a form of mutualism. Due to this behaviour the invasion of vegetation into harsh environments is promoted. The dead remains of insects thrown out by the ants are absorbed by the lenticular warts in myrmecophytes like Hydnophytum...
, meaning “ant-fed,” is the ability of plants to absorb nutrients from debris piles left by ant nests. The tropical tree Cecropia
Cecropia
Cecropia is a Neotropical genus presently consisting of sixty-one recognized species with a highly distinctive lineage of dioecious trees....
peltata obtains 98% of its nitrogen from the waste deposited by its ant counterparts.
Ants as defense
Since plants provide essential resources for ants, the need to protect the plant and those resources is extremely important. Many myrmecophytes are defended from both herbivores and other competing plants by their ant counterparts. Acacia cornigeraAcacia cornigera
Acacia cornigera, commonly known as Bullhorn Acacia , is a swollen-thorn acacia native to Mexico and Central America. The common name of "bullhorn" refers to the enlarged, hollowed-out, swollen thorns that occur in pairs at the base of leaves, and resemble the horns of a steer...
, for example, is thoroughly guarded by its obligate ant partner, Pseudomyrmex ferruginea
Pseudomyrmex ferruginea
The acacia ant is a species of ant of the genus Pseudomyrmex. These arboreal, wasp-like ants have a orange-brown body around 3 cm in length and very large eyes...
. A single colony of P. ferruginea may contain more than 30,000 ants, and can tend multiple Acacia trees. The soldier ants are extremely aggressive, patrolling the trees twenty-four hours a day. Any disturbance to the tree alerts ants, who then recruit more workers from inside the horn domatia. These ants defend the Acacia by biting, violently stinging, and pruning
Pruning
Pruning is a horticultural practice involving the selective removal of parts of a plant, such as branches, buds, or roots. Reasons to prune plants include deadwood removal, shaping , improving or maintaining health, reducing risk from falling branches, preparing nursery specimens for...
any trespassers. The ants keep the plant free from other insects and vertebrate herbivores, but also from invading fungi and other plants.