Observation 89131: Lepraria Ach.

Powdery blue-green film on downed and standing birch, possibly a yellow birch. Also on adjacent poison ivy. Color reminiscent of lichen. Surface appears to be granular.

Microscopy: globose, green stuctures may have cholorphyll; if so this would imply lichen, they are not as frequent as I would expect if spores. Other structures look like fungi to me.

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Which chemistry? Everything!
By: Jason Hollinger (jason)
2012-03-13 18:16:20 PDT (-0700)

TLC is required in some cases. But KOH, bleach, PPD and UV (350nm) are required at least. It’s not an easy group. Color and texture can be of some help, but there are almost always alternatives which can only be distinguished reliably via chemistry.

Have you ever been looking through a dissecting microscope at 30x or higher and suddenly come across an insect? It’s scared the bejeezus out of me a few times! All of a sudden your entire field of view is full of legs and bristles and eyes moving every which way, and the stereoscopic vision makes it pop out at you like a bad 3D horror flick! :)

Thanks Jason
By: Martin Livezey (MLivezey)
2012-03-13 18:03:22 PDT (-0700)

What chemistry would I use? I saw something similar later in the day, but with no fluffiness – just a thin film of the same color on the surface of debarked wood. I did not photograph it, but the soredia have the same look. Maybe that was one of the other species you allude to. I was surprised to see that in addition to soredia, there was a jungle of micro-organisms – protozoa and things much smaller.

Globose structures
By: Jason Hollinger (jason)
2012-03-12 18:27:41 PDT (-0700)

are soredia, made of algal cells embedded in matrix of hyaline hyphae. Microscopy is of limited use in this group. Chemistry is far more important. L. lobificans seems to be the most abundant species in the east, and it’s nice and thick and “fluffy” like this, but could defintely be one of a few other species, too.

Thanks Chris
By: Martin Livezey (MLivezey)
2012-03-12 04:11:30 PDT (-0700)

As near as I can see from MO, I am the only one so far that has posted microscopy. It surprised me that I could not find anything – and here is a word that is new to me – foliose on this one. The other photos indicate that this is entirely possible. Nice to know. Thanks again.

By: Chris Parrish (kitparrish)
2012-03-11 20:24:41 PDT (-0700)

Seems to be a leprose lichen, probably Lepraria. They are widespread on several substrates, and we have begun to accumulate some representative photos on MO.

Created: 2012-03-11 16:37:40 PDT (-0700)
Last modified: 2012-03-12 04:07:40 PDT (-0700)
Viewed: 71 times, last viewed: 2017-06-10 08:37:47 PDT (-0700)
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