What are mycelium, hyphae? What are the connections between the mycelium and plant roots?

The mycelium or mycelium is the body of the fungus. It is made up of threads called hyphae. They consist of oblong colorless cells with a sheath of chitin. By the way of feeding, mushrooms are heterotrophs, that is, organisms that use ready-made organic substances. Many mushrooms obtain them through symbiosis with trees. Germinating into the root, hyphae perform the function of root hairs in old root areas, and in return receive organic matter from the plant. This kind of symbiosis is called mycorrhiza.