Christmas Wreath Lichen

If you take a walk through the Backwoods Forest Preserve at MOSI, you may see a lot of a color you are not expecting. Bright pink to red patches, sometimes several feet in height can be found on many of the oak trees throughout the woods.

Christmas wreath lichen (Cryptothecia rubrocincta) is a species found throughout the Southeastern portion of North America and throughout the tropics and subtropics of South America and the Caribbean. 

This lichen is distinctively colored with a pale green body with brilliant red/pink edging and spots in the center. This color combination and generally circular shape of development have led to its common name of ‘Christmas wreath lichen’. 

The bright red/pink coloring in this lichen comes from chiodectonic acid which is produced by the lichen to help it tolerate inhospitable growing conditions and locations.This species is a crustose lichen which, as the name suggests grows like a crust on the surface of tree bark and other locations. 

This species was first described by a German naturalist named Christian Gottfried Ehrenberg in 1820. The species name, rubrocincta, comes from the red band around the edge of the lichen and derives from the Latin root words ruber "red" and cinctus"girdled/encircled".