Mycorrhizae

Mycorrhizae is the name for the symbiotic partnership between fungal mycelium and the roots of plants: the fungus draws its own nutrition from the root, while in return its extensive hyphal network improves the plant's uptake of water and mineral nutrients from the soil. Three types are recognised. Ectomycorrhizae form a dense fungal sheath (the mantle) wrapped around the outside of the root, with the hyphal network penetrating only the intercellular spaces of the epidermis and cortex to form a structure called the Hartig net (e.g. Pisolithus tinctorius). Endomycorrhizae, in contrast, grow mainly inside the root, penetrating the outer cortical cells themselves, with only a small part of the mycelium remaining outside; because they form vesicle- or arbuscle-like haustoria inside the cortical cells, this form is also called Vesicular Arbuscular Mycorrhizal (VAM) fungi (e.g. Gigaspora). A third category, Ectendomycorrhizae, forms both a mantle and penetrates the cortical cells (examples include Ericoid mycorrhizae, e.g. Oidiodendron, and Orchid mycorrhizae, e.g. Rhizoctonia). Mycorrhizae matter ecologically and agriculturally in several ways: they let the saprophytic angiosperm M …