Sri Lanka is a tropical island situated close to the southern tip of India. It is situated in the middle of Indian Ocean. Lichens are actually a mutual relationship between algae or cyanobacteria with a fungus. Therefore it is a composite organism and not plants. Lichens can be found different shapes and forms. They are grouped by thallus type. Thallus growth forms typically correspond to a few basic internal structure types. Common names for lichens often come from a growth form or color that is typical of a lichen genus. Coloration is usually determined by the photosynthetic component.