Thursday, March 25, 2010

I lichen it!

Walking through the Back Woods Forest Preserve, you may notice bright spots of DSCN0534 pink or red on the bark of some trees. These spots are lichen!

Christmas wreath lichen (Cryptothecia rubrocincta) is a species of lichen 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 and 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".


Wally said...

So, does the amount of red/pink indicate the amount of pollution in the air?

Kristen said...

Hi Wally,

The chiodectonic acid that colors this lichen red is thought to serve as a radiation protectant that works with other substances in the lichen to protect it from UV damage.

Here is more info about Christmas Tree Lichen including its unique chemistry.

In the UK soem lichens are used as bio-indicators to help determine levels of air pollution. In heavily industrialized areas many lichens are absent. In areas near to industrialized areas some particular lichens are likely to be present, but not more delicate ones. In clean air areas all sorts of lichens can be found.

Here's a good article about lichens as bio-indicators: