Type of lichen is a broad term that encompasses many different species of fungi. Stonerag (8 letters) is a type of lichen that grows on rocks and stones, and is usually gray or green in color. Usnea (5 letters) is a type of lichen that is commonly found hanging from tree branches, and is often referred to as 'old man's beard'. Oakmoss (7 letters) is a type of lichen that grows on oak trees, and has a strong, earthy scent. All three types of lichen are important components of the natural environment, providing food and shelter for many species of animals and plants.