Rain.
Easy to identify, but less easy to find, is the wonderful tiny mushroom Marasmius hudsonii which is only found on fallen Holly leaves. Search around under a Holly tree when the black, soft leaves are to be found.
I have always been bemused by the tiny hairs that grow out from the cap, but I think I now have an answer to the question "Why are they there?": notice the water drop on the top of this specimen.
The hairs seem to be a catching mechanism for water: many of the tiny (1-2mm) caps have captured a water droplet.
I liked the under-shot of this one showing the (relatively) thick gills:
This shot is included because I liked the framing effect of the spines of the Holly leaf:
This is another shot to give some idea of scale:
Staying with Holly, the mine of the Agromyzid fly Phytomyza illicis is easily found on the leaves. (In fact I amused fellow musicians the other night when waiting to play at a Christmas concert, I grabbed some Holly leaves from a display and showed them the miner. "Give it a rest, Dunlop, can't you stop doing wildlife even in a Church Hall?". Nope.)
The pupa on this specimen can be clearly seen to the right.
The exclusive association between Phytomyza illicis and Holly has always puzzled me: Holly seems such an ideal place to make a mine, since the leaf spines will serve as extra protection; but no other leaf-miner lives on Holly. I presumed that perhaps Holly has over-protected itself with chemical repellants, but it turns out that Holly - in a similar fashion to all plants - attempts to heal any damage. It does this by creating new tissue and 'filling the gaps' with it. But Holly leaves are very tough-skinned, and the callus is also very hard. That means that any miner that was slow-growing would be squashed by the tree's own healing process. Phytomyza illicis happens to be the only species that is sufficiantly fast to avoid being squeezed to death.