Some form symbiotic associations with algae or cyanobacteria to form lichens, while others form extremely important mycorrhizae with the roots of many plants, including most forest trees.

• 真菌是土壤和淡水中主要的分解者，一些与藻类或蓝细菌共生形成地衣，还有一些真菌与许多植物包括大多数林木的根形成大量的菌根。