The Fascinating World of Lichens

What Are Lichens?

Lichens are composite organisms that arise from a mutualistic relationship between fungi and photosynthetic partners, typically green algae or cyanobacteria. Unlike most organisms you encounter in nature, a lichen is not a single species but rather a stable, self-supporting partnership between two or more entirely different kingdoms of life. The fungal partner, called the mycobiont, provides structure, protection, and mineral absorption, while the photosynthetic partner, called the photobiont, produces food through photosynthesis.

This remarkable partnership has proven extraordinarily successful. Lichens colonize some of the most inhospitable environments on Earth, from scorching desert rocks to frozen Antarctic landscapes. They are among the first organisms to establish themselves on newly exposed surfaces such as bare rock after a volcanic eruption, beginning the slow process of soil formation that allows other plants to eventually take root.

Scientists estimate that lichens cover roughly 8% of the Earth's land surface, making them one of the most widespread groups of organisms on the planet. There are more than 20,000 known species of lichens, and new species continue to be discovered every year. They range in size from barely visible crusts to shrubby structures over a meter tall, and they come in a stunning array of colors including greens, grays, yellows, oranges, and even vivid reds.