tags: lichens, symbiosis, nature, image of the day
Lichens are a symbiotic association between a fungus (the mycobiont) with a photosynthetic partner (the photobiont or phycobiont), usually either a green alga or cyanobacterium. The morphology, physiology and biochemistry of lichens are very different to that of the isolated fungus and alga in culture. Lichens occur in some of the most extreme environments on Earth -- arctic tundra, hot deserts, rain forests, rocky coasts and toxic slag heaps. Lichens are widespread and long-lived; however, many species are also vulnerable to environmental disturbance, and may be useful to scientists in assessing the effects of air pollution, ozone depletion, and metal contamination. Lichens have also been used in making dyes and perfumes, as well as in traditional medicines.