English: This is a cross section of lichen, which is an organism in a symbiotic relationship between green algae and fungus. 1. Thick layers of hyphae, called the cortex 2. Green algae 3. Loosely packed hyphae 4. Anchoring hyphae called rhizines.

Lichen is an organism that is composed of two separate organisms living in a symbiotic relationship. The outside portion of the lichen is a fungus, called the mycobiont, whose job is to provide protection. The fungus is made of strands which are called hyphae. The hyphae is packed into sheets and makes the upper surface which can be seen by the naked eye. This is called the cortex. Anchoring hyphae, called rhizines, attach the lichen to the rock or tree that it is living on. A different organism is inside this protective barrier. A green algae, called the photobiont, sits in clusters between the two walls. The algae photosynthesize to produce the sugar needed by the entire lichen. Strands of hyphae hold the algae to the fungus wall.

Reference Websites http://autocww2.colorado.edu/~toldy2/E64ContentFiles/AlgaeAndFungi/Lichen.html

http://www.lungtp.com/bioticfactor/d_lichen1.jpg