Observation 50081: Graphis Adans.

When: 2010-08-09

Collection location: Parque de Monsanto, Lisboa, Portugal [Click for map]

Who: zaca

No specimen available

Living on a tree. First I thought that maybe Graphis scripta. However, the chemical reactions are not according to what is mentioned in the description of that species given in the reference, which indicates K-. I was not able to find a species in Graphis with a K+red reaction.



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Someday I will try.
By: zaca
2010-08-10 18:57:30 CDT (-0400)

Thanks, Jason, for the explanation.

sectioning lirelloid apothecia
By: Jason Hollinger (jason)
2010-08-10 17:38:00 CDT (-0400)

It is renowned for being very difficult. I personally recommend slicing somewhat diagonally, but I’ve heard Bill Hill recommend slicing lengthwise. My issue with that is that I don’t have enough experience to diagnose the anotomy of the apothecium when sliced so obliquely. But slicing cross-wise doesn’t give you enough material to find a spore. Doing it diagonally gives you a longer section, and exagerates the features of the walls.

Note that many are spectacularly narrow, long, twisty things. Others are “ropaliform” or comet-shaped. Another thing that I had trouble with at first is whether the cells of the spores are thin-walled or thick-walled. I was worried that a thin-walled spore with oil-drops in the cells could appear thick-walled, but this seems rarely to actually be the case. And besides, thick-walled spores are typically obviously so, with weird angular or lens-shaped compartments. Some spores (such as those of Graphis scripta, which I agree yours cannot be) are very beautiful and rewarding, making the effort worth it.

I was not aware of such variety …
By: zaca
2010-08-10 17:06:05 CDT (-0400)

but, since I find the first (only three days ago), I had observed a lot of different sort of script lichen. Now I know what to look for: some ovoid(sometimes round) clear spots in smooth barked trees. Some are really spectacular!
Because of the shape and sometimes the imersion of the fruting bodies in the thallus, is there any special preparation to observe the spores? More precisely, how to prepare a slide to observe under the microscope?

script lichens are another hard group
By: Jason Hollinger (jason)
2010-08-10 14:39:16 CDT (-0400)

Most are in Graphidaceae (e.g., Graphis, Glyphis, Phaeographis, Fissurina) and Opegraphaceae (e.g., Opegrapha, Enterographa, Lecanographa). But there are a few other genera to consider, like Schismatomma and Arthonia. Spore shape and size are important, as well as anatomy of the lirellae (e.g., are the walls black? are paraphyses present? etc.) On top of everything else, it can be hard to get access to literature.

Created: 2010-08-09 20:01:56 CDT (-0400)
Last modified: 2010-08-14 14:38:59 CDT (-0400)
Viewed: 114 times, last viewed: 2016-10-03 12:04:52 CDT (-0400)
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