Before chucking out the sad remains of the Malva moschata flowers, I did a last attempt to make the UVIF record of its coronavirus-alike pollen grains.
This time with a Convoy UV LED torch, Mitutoyo 20x/0.42 objective and the Z7. The stack length was 151 frames, yet due to the irregular 3-D distribution of the anthers I couldn't make the stack as deep as I had wished. Oh well. I'll find something else to do. Further Malva is out.
My impression is that the damaged pollen grains are those showing the highest degree of fluorescence. Don't ask me why -- I'm just the photographer here.