Between a rock and a hard place

I passed this spectacular display of fungi on my way to work this morning, growing between a brick wall and the pavement.

I was just amazed to see this densely-packed mass of mushrooms, bursting through the tarmac.

The patch on the left were clearly a day or two older than the rest, in shades of brown and beige, while the younger fruit bodies were a bright, lustrous tan colour.

The youngest fruit bodies, where they had some shelter from the elements, looked like they had spiky little white skirts. What style!

I must be getting better at this mycology malarkey, because I think my initial guess at their identity – a Psathyrella of some kind – was correct. This strongly clustered growing habit is typical of the Clustered Brittlestem Psathyrella multipedata.

I had a look at one of the fruit bodies and it seemed a good match for P. multipedata.

If you look closely, you can see the cap is "faintly striate halfway towards the centre".

Funga Nordica describes the veil as "scattered fibrils near the margin": the spiky white skirt I'd seen in the photo above. There's a German website – vielepilze.de – which includes comprehensive information on the European Psathyrella; it describes the veil as "very volatile, mostly only visible in youngest stages, often absent" which also fits with what I've observed.

The young gills are pale brown and crowded.

The key to the Psathyrella in Funga Nordica (which you can access through MycoKey) says that the gill edge and cystidia are "covered with drops staining green in a solution of ammonia". I've got some ammonia, I bought a massive bottle of it at the hardware shop in the village. So I thought I'd give this a try.

I think this might be my MOST EXCITING GILL SQUASH yet. Not only is the gill edge covered in attractive bottle-neck-shaped ('lageniform') cystidia, but they went green! I quickly measured the spores as well, and made them about 7 microns.

I think I'm on pretty safe ground calling these mushrooms Clustered Brittlestem Psathyrella multipedata.

The habitat does seem a little odd though. Funga Nordica describes this species as occurring "on soil, usually attached to buried wood, on stumps, in forests or parks ..., [or] on calcareous or nutrient rich soil, in grass lawns and on sawdust". But Roger Phillips describes the habitat as "amongst grass in open deciduous woodland and on roadsides." – which fits better with where I found them.

For the record
Date: 18/09/2017
Location: Small Dole
Grid reference: TQ2113

Record entered into FRDBI 06/09/2018