Part 1
Introduction Lichens are epiphytes occurring in most environments of the world. They are commonly found on soil, trees, leaves, and even bare rock. They are found in mesic environments, potentially long lived and are poikilohydric. They are a product of the symbiotic relationship of photosynthetic acyanobacteria and a fungus (most commonly an ascomycete). The symbiotic relationship may be of various types such as mutualism, commensalism, or parasitism. The outer layer is known as the cortex and is composed of photobiont cells. The inner layer, known as the medulla, is composed of loosely arranged hyphae. Below the medulla is a lower cortex ...
