arbuscular mycorrhizal association arbuscular mycorrhizae formation bf arbuscular mycorrhizas formation GO:0036377 arbuscular mycorrhizal symbiosis 2013-05-07T15:07:32Z A form of mutualism between a fungus and the roots of a vascular plant, where hyphae of the fungus penetrate the plant cell wall and invaginate its cell membrane. Once inside, the fungus forms highly branched structures for nutrient exchange with the plant called arbuscules. Aids in the acquisition by the plant of nutrients such as phosphorus from the soil. biological_process biological process involved in symbiotic interaction