Forest mushrooms comprise the largest category of macrofungi found in Arkansas, as well as throughout the world. The name implies that these mushrooms are found only in forests and in close proximity to trees. This group of mushrooms is classified as ectomycorrhizal – a term derived from the Greek words “ecto” (outside), “myco” (fungus), and rhizo (root). Ectomycorrhizal fungi produce filaments called hyphae that form a sheath of mycelia (tangled masses of hyphae) around the tips of roots of various trees. This relationship usually is classified as symbiotic because both organisms benefit: the fungus receives carbon in the form of sugars and other organic substances from the tree, and in return the fungus assists the tree in the uptake of water, minerals, and fungal metabolites. Because this relationship can be a necessary partnership where each organism needs something from its partner to survive, if one party dies, the other will suffer greatly and may also die. If the tree symbiont is destroyed or dies, then the fungus will die. If the fungus dies, then the tree will weaken and may be susceptible to diseases and may also eventually die. Genera of ectomycorrhizal mushrooms that are common in Arkansas include Amanita, Russula, Lactarius, Boletus, Cantharellus, and Tricholoma.