Tree growth is the process of a tree increasing in size and height over time. It is a complex process that involves many different components, such as MOSS, LICHEN, knur, LEAF, and BURL. MOSS is a small, soft plant that grows in moist environments and can be found on tree trunks and branches. LICHEN is a composite organism composed of a fungus and an alga that grows on rocks, trees, and other surfaces. Knur is a type of bark that is rough and scaly and is often found on older trees. LEAF is the main photosynthetic organ of a tree, which helps it to absorb sunlight and convert it into energy. Finally, BURL is a type of wood growth that is characterized by a knot-like pattern and is often used for decorative purposes.