Interactions between higher plants and micro-organisms in natural ecosystems are among the most common and useful types of interaction between genetically distant organisms. Examples are associations of flowering plants with fungi forming Glomeromycota arbuskularną mycorrhizae , as well as more specialized legume endosymbiosis of soil bacteria belonging to the species of Rhizobium . Research paleontological fossils and phylogenetic estimates indicate that mycorrhizae can occur at the same time as terrestrial plants .