Lichens are composite life forms created by a symbiotic relationship between an algae or a cyanobacteria and a fungus. The algae or cyanobacteria are photosynthesizing life forms which provide sugars to the fungus, which in turn provides protection, water collection and minerals to the photosynthesizing partner. Lichens are found throughout the world in a large variety of environments from tropical rain forests to deserts and the Arctic tundra. Lichens absorb moisture from the air and in that process they absorb pollutants as well. They are not tolerant of pollution so lichens, or more precisely the lack of lichens, have been used as rough approximations of air pollution. They grow very slowly, only about a millimeter a year and can be very long lived. There around 20,000 species of lichens world wide and they take on a number of morphological expressions such as fruticose, foliose, crustose, leprose and several others.

This series of images of lichens was created from photographs of the large variety of lichens found at the Castroville Regional Park at Castroville, Texas. While lichens come in a large variety of colors these images were created in a black and white color space to focus on their varied shapes and textures.

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