Moss and Lichen. Mosses and lichen growing on and around the trunk of a beech tree. The tree trunk is covered with lichens (white and light green) and mosses (dark green). Mosses can also be seen around the trunk (far left, lower right) and among leaves shed by the tree (lower frame). Mosses are small plants without roots or woody, water conducting stems. A moss will typically grow in dense mats on trees, rocks or damp ground. Lichens are an example of symbiosis. Fungal and algal cells cohabit for mutual benefit and make up the body of the plant. Photographed in Northumberland, England.