Glomeromycota (informally glomeromycetes) is one of seven currently recognized divisions within the kingdom Fungi, with approximately 230 described species. Members of the Glomeromycota form arbuscular mycorrhizas (AMs) with the roots or thalli (e.g. in bryophytes) of land plants. Geosiphon pyriformis forms an endocytobiotic association with Nostoc cyanobacteria. AM formation has not yet been shown for all species.