Story behind the art of Susan Benjamin

Curious Allies: Mutualism in Fungi, Parasites, and Carnivores

The Fifth New York Botanical Garden Triennial

Green Shield Lichen

Flavoparmelia caperata

One of the most common lichens in North America is the common greenshield, Flavoparmelia caperata. It looks like a lettuce leaf attached to the side of a tree. Its upper surface is usually pale yellow-green when dry, and a deeper green when wet. It has round-edged lobes that are smooth when it is small but wrinkled when it becomes larger. I enlarged my image of the lichen 10 times and was amazed at the beautiful intricate wrinkling of the lobes near its center! I was ready to take up the challenge of painting this small organism.

This lichen is composed of the fungi Lecanoromycetes (including Parmeliaceae) and Lecanorales and a green alga. The lichen uses the bark on the tree as a place to live and grow, but does not penetrate the inner bark of trees and takes no nutrients or water from the tree.

Lichens are very sensitive to pollution. Therefore, the more lichens, the cleaner the air is in the vicinity. The common greenshield is relatively tolerant of air pollution, so it will likely be one of the few species in moderately polluted areas. 

Long before anyone was concerned about air pollution, people came up with a few other uses for this lichen. The Tarahumara people of northern Mexico ground the lichen into a powder to treat burns. In Europe and parts of Asia, the lichen was used to dye wool. Dye made from the common greenshield imparts woolen fabrics with a color anywhere from lemon yellow to brown orange.

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Read more about this artist's work: 24th Annual