Mycorrhizas, or "fungus root" are fungi that live in a close symbiotic relationship called mutualism, with trees found in the forest. As the trees carry out photosynthesis, some of the carbon is given to the fungi. Fungi, on the other hand provide additional nutrients for the trees and help them get more water than their own root system can accomplish. Fungi are able to extend the root system of the plant, enabling the plant to gain access to more water and nutrients than would be possible alone. Another relationship is between trees and moss or algae. Sometimes, moss or algae grow on the side of a tree, which is benefical because they can receive more light than would be available on the forest floor amongst the leaf litter. It is an example of commensalism because the tree is neither harmed nor helped by this relationship.