Tuesday, December 13, 2011

White Spots on Trees

Recently I've been noticing the various white spots found on the bark of trees.  Many of these spots are actually crustose lichens of one sort or another, growing within the upper bark tissue.
Many of these white, splotchy, bark dwelling lichens sport various black spots or squiggles (apothecia in various shapes).  These features can aid in identification, but ultimately it seems that a microscope is needed to make any kind of exact identification.
To make identification more difficult, there are also unlichenized fungi that look very similar growing on the bark of the trees
I suppose they aren't much to look at, but they do add a bit of contrast to the woods, especially this time of year in Minnesota.  But what I think is interesting is that they are fairly common and easily seen, but largely unknown to most of us.



  1. Good stuff, maybe you can help us identify some mushrooms we found on our hike today.

  2. Beautiful! Looks like Graphis scripta or a similar species. I've been obsessed with those since I learned about them!

    1. Thanks for the comment. It does very much resemble Graphis scripta, but didn't quite match when I looked it up in "The Lichens of North America". There are a number of other similar genera (Arthonia, Buellia, Conotrema, etc). Whatever their identity I agree that they are beautiful. I went through a big obession with white crustose lichens on trees this past fall!

  3. Lab tests clearly show the white is not Lichen but metals. Bark taken from the tree with that type of white spots was tested for aluminum, barium, strontium and titanium and the testing came out positive for all four substances. On an initial test, Aluminum was highest (387 mg/kg), and on another one was 435 mg/kg.

    Results of Bark sample taken in September 2009: Aluminum 387 mg/kg, Barium 18.4 mg/kg, Strontium 113 mg/kg, Titanium 15.2 mg/kg. See more info http://www.aboutthesky.com/tree-decline

  4. So wondering what can be done...because because my aguacate tree looks like.that, full.of white spots....would b dangerous for the fruit? Ty