I have attempted take better micrographs of the ascus tip in Xanthoria parietina.
How do my attempts compare with the published diagrams?
Thread https://twitter.com/obfuscans3/status/1388175439911346185

First here is a section through the hymenium mounted in water. An impression of spores within the asci can be seen below the surface layer of orange brown granules.

Here is the same after adding K. This pre-treatment is required to loosen the structure of the hymenium by dissolving the hymenial gel. Without this, we won't be able to separate out individual asci.

Heating helps hasten the pre-treatment. (The spores are now fully 'cleared' and they can be seen to be composed of two cells, with a very thick central septum.)

Now I have flushed with acetic acid and then added dilute Lugol's iodine solution. The starchy (amyloid) parts of the ascus tip have stained blue.

The Teloschistes-type ascus as illustrated in LGBI2 and my attempt. Never as clear as it appears in drawn illustrations but basically showing the same structure.

Even with watered down Lugol's it is very easy to overstain as here, where the fine structures are obscured by the intensity of the staining.

Now I have another section, mounted in K. In this part of the apothecium there are numerous paraphyses, visible as glassy vertical strands between the asci.

This time I have stained using ink. This acts in a totally different way to iodine. It fills the lumina of the hyphal cells, making the paraphyses easier to visualise. The ascus tips are not stained.

Now I have added Lugol's iodine so we have two types of blue staining. Unfortunately, even though the iodine was very dilute, it was too strong and has over-stained. It is difficult to get ascus tips stained to perfection.

The nature of the ascus tip is often important in arriving at the correct genus but it is a technique which many shy away from. It requires observation at high power and much patience.

https://twitter.com/obfuscans3/status/1155533417884323840