Mycorrhiza

A mycorrhiza (typically seen in the plural form mycorrhizae meaning "fungus roots") is a specialized form of hyphae that extends from the mycelium of a fungus into the roots of a plant.

Mycorrhizae form a mutualistic symbiotic relationship with the roots of 95% of all vascular plants. This association provides the fungus with a renewable source of food, and allows the plant to make use of the mycelium's tremendous surface area to absorb nutrients from the soil. Mycorrhizal fungi explore a larger volume of soil than root systems at a lower cost to the plant. Some of the earliest fossil plants show evidence of mycorrhizae associated with them. Mycorrhizal plants are generally more resistant to diseases e.g. caused by microbial soil-borne pathogens and are also more resistant to the effects of drought

Some mycorrhizal hyphae enter within the plant cell's wall and grow to envelop the cell. However, most mycorrhizae have a more advanced structure, in which the hypha lives inside an extensive invagination (inpocketing) of the cell membrane.