Lichens are composite organisms consisting of a fungus and an alga or cyanobacterium living together in symbiosis.
Lichens are slow-growing, durable, and can thrive in extreme environments with limited water and nutrients.
Lichens have three main parts: the mycobiont (fungal component), the phycobiont (algal or cyanobacterial component), and the thallus (the main body of the lichen).
There are three main types of lichens: crustose (crust-like), foliose (leaf-like), and fruticose (shrubby).
Lichens reproduce both sexually (through fungal spores) and asexually (through fragmentation or vegetative propagation).
The mycobiont and phycobiont have a mutualistic relationship, where the fungus provides protection and water, and the alga or cyanobacterium photosynthesizes and provides nutrients.
Lichens play a crucial role in nutrient cycling, soil formation, and as indicators of air pollution.
Lichens can grow on various substrates, including rocks, trees, soil, and even metal surfaces.
There are over 20,000 known species of lichens, with diverse forms, sizes, and colors.