mycorrhiza

The tree and fungus both benefit from their symbiotic relationship.

Mutually beneficial (mutualistic) association occurring between plant roots and a soil fungus. Mycorrhizal roots take up nutrients more efficiently than non-mycorrhizal roots, and the fungus benefits by obtaining carbohydrates from the plant or tree.

An ectotrophic mycorrhiza occurs on many tree species, which usually grow much better, most noticeably in the seeding stage, as a result. Typically the roots become repeatedly branched and coral-like, penetrated by hyphae of a surrounding fungal mycelium. In an endotrophic mycorrhiza, the growth of the fungus is mainly inside the root, as in orchids. Such plants do not usually grow properly, and may not even germinate, unless the appropriate fungus is present.

Research by UK ecologists in 1996 showed that mycorrhizal fungi provides protection against nematode worms that feed on plant roots, as well as pathogenic fungi. Further research in 1998 showed that diversity of mycorrhizal fungi in the soil contributes greatly to plant biodiversity.