[poschiavanus]

JP, if its fruiting, i.e., has apothecia or perithecia, the best thing is to, wait for it, look at the spores!

A good place to start is with Xanthoria parientina, using a half safety razor blade cut a thin section and make a temporary mount in water. You have a good chance of seeing spores and the structure of the hymenium just as you would with any other asco (x 400). Dont have the details in front of me, but theyre probably on Alan Silverside's site.

Its way easier to discriminate between various structures under the dissecting microscope (particularly whether sorediate or isidiate). With a section you can also see where the algal cells are located (possible but not so simple with a hand lens).

Have fun,

posch