This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
When I was in Florida a few weeks ago, I visited the Audubon Society's Corkscrew Swamp Sanctuary (highly, HIGHLY recommended should you be in southwest Florida), which features a two and a quarter mile boardwalk through old-growth cypress swamp. Bald and pond cypress towered over a swamp filled with alligators, snowy egret, and white ibis. We got to see a six-foot alligator and her progeny through a spotting scope. For the plant enthusiasts, there were 500 and 600 year old cypress, strangler figs perched in their treetops, swamp lillies, and cypress knees -- woody protuberances that stick up from the swamp from the roots of the cypress.
But the strangest sight of all were the lichens I noticed peppering the railings of the boardwalk that led us through the swamp, and the bark of the occasional tree. They had bright red borders and sometimes speckled centers on either a white or green ground. I had to know what they were. When I got home and looked them up, I discovered they were called "Christmas lichens", or Christmas wreath lichens". And so I use these photographs to wish you a happy Christmas, should you happen to celebrate it. Here they are (along with a fascinating assembly of other lichens and mosses that leave no wooden surface uncovered in the heart of the swamp):
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Here's a closeup of a slightly different section of the railing:
What a spectacular and unexpected sight! Here we have another strange red pigment, like the prodigiosin produced by Serratia marcescens that I wrote about earlier this year. This red pigment is chiodectonic acid, which like many lichen chemicals likely serves as a UV protectant. Beta-carotene (which might help with DNA repair after exposure to UV) and chlorophyll are also found in the bright red areas. For some more lovely photographs of Cryptothecia rubrocincta (the species epithet means "red-girdled" or "red-wreathed") that show the green of the red/green Christmas lichen a little better, see here.
Merry Christmas!