Lichen

Description:

Is a composite organism that emerges from algae or cyanobacteria (or both) living among filaments of a fungus in a mutually beneficial (symbiotic) relationship. The whole combined life form has properties that are very different from properties of its component organisms. Lichens come in many colors, sizes, and forms. The properties are sometimes plant-like, but lichens are not plants. Lichens may have tiny, leafless branches (fruticose), flat leaf-like structures (foliose), flakes that lie on the surface like peeling paint (crustose), or other growth forms. A macrolichen is a lichen that is either bush-like or leafy. A microlichen is everything else. Here, "macro" and "micro" do not refer to size, but to the growth form. Common names for lichens may contain the word "moss" (e.g., "Reindeer moss", "Iceland moss"), and lichens may superficially look like and grow with mosses, but lichens are not related to mosses or any plant. Lichens do not have roots that absorb water and nutrients as plants do. Instead they produce their own food from sunlight, air, water, and minerals in their environment. When they grow on plants, they do not live as parasites but use the plants only as a substrate.

Habitat:

Because lichens do not have a waxy cuticle like plants, they cannot conserve water during drought periods. On the other hand, lichens can absorb everything through their cortex, including water and water vapor. Many lichens are found in foggy areas like the coast, but not farther inland simply because there is not enough water in the air to support them. When lichens are wet, they "turn on" and start photosynthesizing and growing. When lichens are dry, they "turn off", become brittle and go dormant. This process is known as "poikilohydry", and other organisms such as mosses and liverworts operate in the same way. Additional Information: Lichens are remarkable in that they can tolerate the most extreme environments, thus they can live in hot dry places as well as arctic conditions and the wettest of rain forest. Although they can tolerate salt spry and immersion in water they are not aquatic. Lichens can live on soil, woody debris, rocks, tree bark, tree leaves, other lichens, desert sand, animal bones, and rusty metal. For this reason they are nature's pioneers. Been first to colonise the most inhospitable places from there they begin the slow process of creating the foundation for other habitation.