A Micro Fungus.

I have been interested in rust fungi for a while now, but the search for them has led me into, taking an interest in other microfungi, a group which includes rusts, mildews and soots, but also things that look like miniature versions of the fungi we are all familiar with. It is a world that requires hand lenses in the field and microscopes at home, as identification often comes down to studying the spores (more interesting than might be imagined). Often the view down the microscope is breathtakingly beautiful, but can be frustrating too. Winter isn't the best time to go looking for specimens to collect for study, but there are some to be found and with them can sometimes come bonus species, such as this epiphyllous alga, found while searching the leaf litter beneath a shaded Laurel. The tiny dull olive disks of it were scattered over the upper surface of the fallen leaf. At home I found they pealed off readily and were easy to mount on a slide, but very difficult to do so without trapping air bubbles on or against them.

Part of the Alga (Phycopeltis arundinacea) From the surface of a Laurel Leaf, Collected
 from the Leaf Litter. X400 (unstained)

Phycopeltis arundinacea, X100, Stained with Methylene Blue.
The whole colony is 1.10mm across its widest point.

Phycopeltis arundinacea, from a Laurel Leaf. Stained with Methylene Blue. X200.  

I am a raw beginner at this and the vast majority of microfungi are still beyond me, but the more obvious and distinctive ones can often be tackled successfully, particularly as many of them are host specific. Back in 2013, when I was actively square bashing Cobalt Crust fungus and searching the deepest recesses of Sallow thickets, I often came across what looked like a coarse, black stubble, on dead twigs and branches of the Sallows. Through the hand lens, I was intrigued to see that the tiny fruiting bodies which made up the stubble were shaped like minute chisels or perhaps more like Neolithic polished flint axe heads (up to 2mm long), sticking up from the surface of the bark or wood at various angles.
Since then I have tried to identify them, but without success and even when I bought the Bible of Microfungi: 'Microfungi on Land Plants' by Martin and Pamela Ellis, I was disappointed when I was unable to find it under Salix (willow Spp). 
Googling 'Microfungi of Salix' got me nowhere either, until New Year's Day. As I poked around in Dare Valley country park, I came across this fungus again and collected a specimen to examine under the microscope and when I got home I tried an web search again, but this time, armed with a little more knowledge of types of microfungi, I searched on 'Ascomycetes on Salix' and bingo, there were loads of pictures of it.

At last, I had its name: Glyphium elatum, so was able to go back to the book and look it up. According to the Ellis's, they have only ever seen it once, on Honeysuckle in the Channel Islands, though they mentioned that it also occurs on other woody species, it is listed under Honeysuckle in the book, which is why I failed to find it in there the first time
. They regard it as rare, but around here, it is fairly common on Sallow and I seem to recall seeing it on dead Wych Elm too. Either way, I think I now have my new square bashing project for this winter.

Above is my first attempt at a stereo pair of Glyphium elatum, which I made by photographing the specimen through the left, then the right eyepieces of my stereo microscope on x20 and then stiching the cropped images together. 
If you've never viewed one of these before, you need to fix your eyes on the central join and cross them until the two halves merge into a central 3D image. It takes a little practice, but worth it, even if my effort isn't as good as I'd hoped. You will probably need to click on the photo to open it first.
If you want to see some really excellent stereo sets of Glyphium elatum, take a look here.  http://www.eboehm.com/glyphium.html