DENDROLOGY

Detailed explanation-1: -A lichen is a combination of fungus and/or algae and/or cyanobacteria that has a very different form (morphology), physiology, and biochemistry than any of the constituent species growing separately. The algae or cyanobacteria benefit their fungal partner by producing organic carbon compounds through photosynthesis.

Detailed explanation-2: -lichen, any of about 15, 000 species of plantlike organisms that consist of a symbiotic association of algae (usually green) or cyanobacteria and fungi (mostly ascomycetes and basidiomycetes).

Detailed explanation-3: -Lichens are the symbiotic associations i.e; mutually useful associations between algae and fungi. The algal component is known as phycobiont and the fungal component is known as mycobiont, which are autotrophic and heterotrophic respectively.