The Biology of Lichen

Lichens are fascinating and complex organisms that play a significant role in the biogeochemical cycle on Earth. They consist of two or more diverse organisms, i.e. a fungus and an alga. These organisms live together in a symbiotic relationship where they are mutually beneficial. The fungus benefits from the photosynthetic activity of the alga. In return, the alga is protected by the filaments of the fungus. Lichens can reproduce by fragmentation, where a fragment of the lichen breaks off from the thallus to form a new individual. They can also reproduce by forming tiny, dust‐like spores. These spores can be carried long distances by the wind. They are cosmopolitan organisms that grow in all ecosystems on Earth. Lichens can tolerate extreme environmental conditions. Lichens can monitor air pollution and climate change. Lichens are an important food source for many herbivores, such as reindeer and caribou. Lichens help to prevent soil erosion. Several species of lichens are used in traditional medicine as an antibacterial, antiviral, and anti‐inflammatory agent. Some lichens are used in perfumes and fragrances for their unique earthy scent. Many lichens provide natural dyes for textiles and other materials. © 2024 John Wiley & Sons Ltd. Published 2024 by John Wiley & Sons Ltd.