Red Lichen, Christmas Lichen, Christmas Wreath Lichen

09 Feb

Herpothallon rubrocincta (better known as Cryptothecia rubrocincta)

John and I drove to the fringe of the Everglades today, to the huge Arthur R. Marshall Loxahatchee National Wildlife Refuge near Boca Raton, where they are celebrating Everglades Day tomorrow (2/10/18). CLICK

Marshall 1

The theme of the upcoming event is “colors of the Everglades.”  Based on today, the feature color should be red:  as in a vermilion flycatcher showing off its vermilion, Virginia creeper and poison ivy bloody winter leaves,  well named cardinal airplant, northern needleleaf with its red inflorescence,  scarlet young  peppervine, and what seems to be an escaped epiphytic cactus glowing reddish in the cypress swamp.

The selected red item in today’s spotlight is the spectacular lichen sometimes called Christmas (Wreath) Lichen.   It makes me want a Dunkin Donuts strawberry frosted donut.

Red Lichen 2

Red lichen loves wet woods and swamps.  Photo by John Bradford.

Now it could be time for a windy monologue on what lichens are all about.  I don’t feel like doing that;  that is all over the Internet already.  So now suffice it to say that a lichen results from the symbiotic relationship of a fungus (or more than one, as probably in the present case) and an alga (or a blue-green “alga”). CLICK for Wikipedia

Red Lichen 1


Why would a humble lichen be so magnificent?   If a lichen is beautiful in the woods and nobody sees it, is it still lovely?   Botanists agree that the red is probably sunscreen, as is the red in the young growth of many ferns and seedplants, such as that peppervine mentioned above.  The red pigment from the lichen, chiodectonic acid, increases in concentration when the fungus experiences UV exposure.   You might say the lichen gets a sun-tan when exposed, as I might on a tropical vacation.


Peppervine, red when young

This species has a second oddity, shared with other lichens and with mammalian urine sometimes:  calcium oxalate crystals.    You can discuss how and why that happens with your urologist.  But why would a lichen make bladder crystals? It has no kidneys. CLICK to see canine bladderstones.

Calcium oxalate from Cryptothecia - Copy

From a bladder, or from a red lichen? You guess. (From red lichen.)

Nobody really knows  why or how the lichen gets its crystals, given its tree trunk lifestyle, having no roots in the ground.  The calcium apparently arrives in rain,  stemwash, and dust.   Could a lichen living on pixie dust accumulate so much excess calcium it needs to sequester the mineral as hunky crystals?   Possible but seems unlikely.   More fun ideas have been put forward:

With the help of these corrosive crystals, lichens are known to degrade limestone monuments.  It has been suggested that the crystals help lichens on rocks dissolve nutrients from their substrates, or in the case of a lichen on a treetrunk, help the fungus release nutrients from windblown minerals and from particles in stemwash.

A more mundane yet plausible explanation is to shield the delicate algae held below the crystal layer, especially from drying.  This notion has the support of the mutual positions of the crystals and algae.

Red lichens seem to be playground bullies.  I get the impression that they win upon glacial collisions with different species,  little seems to start growing on the red lichen surface,   and research suggests the lichen can suppress Tillandsia airplants.

Trentepohlia from Cryptothecia

Microscope view of the green alga partner,  in center,  liberated from the fungus (seen as fine strands).  A crystal or two photobombed the shot.





Posted by on February 9, 2018 in Christmas Lichen, Uncategorized


9 responses to “Red Lichen, Christmas Lichen, Christmas Wreath Lichen

  1. Laura Corrigan

    February 9, 2018 at 7:57 pm

    I just love sat and tea…plus botany…now I Know why you are so passionate for botany…it’s contagious…thank you Dr Roger’s…

    • George Rogers

      February 10, 2018 at 7:42 am

      Good morning Laura…thanks

  2. theshrubqueen

    February 9, 2018 at 8:11 pm

    Sounds a little like politics…fascinating as usual. I would have thought red paint on the tree trunks, not lichens.

    • George Rogers

      February 10, 2018 at 7:43 am

      Right…looks like a paintball splat. Not as much of the red one up in your general direction it seems to me.

  3. Uncle Tree

    February 9, 2018 at 8:23 pm

    Really? 😉 That tree has skin like me. I shed more bark than I make.

    • George Rogers

      February 10, 2018 at 7:44 am

      It does look like something a dermatologist might love.

  4. Marge Drake

    February 10, 2018 at 6:30 am

    Always look forward to this blog. Great photos, information and sense of humor.

    • George Rogers

      February 10, 2018 at 7:45 am

      Thank you Marge! Such a nice note to find 🙂

  5. Steve

    February 18, 2018 at 5:34 am

    I know those trees (and lichens). They are quite striking, and very “photographable”. I must have a 15 year old picture of the same site buried deep in my digital docs. Yay Everglades!


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