upright=1.35|thumb|[[Pseudomyrmex ferruginea ants on a myrmecophyte tree, Vachellia cornigera, the bullhorn acacia of Central America]]
Myrmecophytes (; literally "ant-plant") are plants that live in a mutualistic association with a colony of ants. There are over 100 different genera of myrmecophytes. These plants possess structural adaptations in the form of domatia where ants can shelter, and food bodies and extrafloral nectaries that provide ants with food.
Mutualism
thumb|[[Crematogaster ants nesting in Macaranga bancana stem]]
Myrmecophytes share a mutualistic relationship with ants, benefiting both the plants and ants. This association may be either facultative or obligate.
Obligate
In obligate mutualisms, the organisms involved are interdependent; they cannot survive on their own. An example of this type of mutualism can be found in the plant genus Macaranga. All species of this genus provide food for ants in various forms, but only the obligate species produce domatia.
Facultative
In facultative mutualism, the survival of the parties (plant and ants, in this instance) does not depend upon the interaction. Facultative mutualisms most often occur in plants that have extrafloral nectaries but no other specialized structures for the ants. Different Acacia species 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. Tubers form when the hypocotyls of a seedling swells to form a hollow, chambered structure that can become inhabited by ants. Food bodies are identified by the main nutrient they contain and by the genus of plant producing them. 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 (Myrmecia urens).
Ants and seed dispersal
thumb|Afzelia africana seeds bearing orange [[elaiosomes]]
Myrmecochory, "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.
A 2014 study by Chanam et al. showed how domatia could evolve without a specialised protection-based symbiosis. Nutritional benefits can be provided by multiple species of ant (including protective, non-protective and even plant-damaging species) and other invertebrates. The myrmecophyte Humboldtia brunonis sometimes bears domatia, whereas all individuals produce extrafloral nectar. Domatia-bearing H. brunonis plants have greater fruit set and hence greater reproductive success, than those without domatia. Plant tissues near domatia received additional nitrogen compounds from the harboured species.
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 symbionts.