The Glomeromycota are mycorrhiza forming fungi. Mycorrhiza (literally
fungus-root) are mutualistic association of fungi with plant roots and the vast majority of plant species (probably >95%) are associated with mycorrhizal fungi; strictly speaking, plants do not have roots, they have mycorrhiza. The most widely distributed mycorrhizal 'type', both through the plant kingdom (formed by about 80% of all vascular plants) and geographically, is an endomycorrhiza formed by the Glomeromycota and called arbuscular mycorrhiza (AM). In this, hyphae colonize plant cells and produce finely branched structures (the arbuscules). This symbiosis feeds most land plants, the arbuscules facilitating nutrient exchange and water uptake and, by carbohydrate transport to the soil, also represent a relevant terrestrial carbon sink.