Physarum Album ? Physarum leucophaeum ? at Strumpshaw Fen – Winter 2025/26

Part way through drafting this post, poring over the photos, I realised that I was probably looking at not just likely Physarum album but also another likely Physarum species, and that forms that I had previously ID'd as likely Physarum album were probably not all Physarum album.

I had to take a deeper look into my books and online resources, and began to feel more confident of what Physarum album likely is, macroscopically.

20th December 2025

The Dell

Turning over the branch fragment, I uncovered a gregarious colony of bluish-grey and greyish-white sporangia.

Two key characteristics of Physarum album that I didn't fully appreciate previously...

"the nodding, lenticular sporangia with petaloid dehiscence"
"Stalk: long, usually twice the diameter of the sporangium, tapering" [1]

"subglobose or lenticular, usually nodding"
"Stalk... slender, tapering, longitudinally wrinkled" [2]

...do not appear to describe these sporangia — the sporothecae are more globose, perhaps larger, have thicker, shorter stalks, and are not nodding.

Based on [1] & [2], this slime mould could be Physarum leucophaeum.

21st December 2025

Near The Outpost

On the same downed trunk where we observed a fabulous plasmodium to mature sporangia transition of Badhamia utricularis — the daughter spotted a gregarious group of dehiscing sporangia (which I would have missed).

These have a petaloid dehiscence and long stalks, but difficult to discern if they are nodding. So are these Physarum album? What is curious are the odd sporangia — with similar stalks — but with glossy black sporothecae. These do not look like black spore masses, but rather intact sporothecae at an earlier stage of maturation — their peridia are still moist.

Do these black sporothecae represent a stage in the development of Physarum album — before the sporothecae mature to a pale grey — or maybe this is not Physarum album...?

The mystery of the glossy black sporothecae would become clearer when I reviewed the photos of a small sporangial cluster on a decaying trunk along the Drainage Channel Path...

22nd December 2025

Drainage Channel Path

These sporangia on a wood fragment were a wonderful find — yet another group the daughter spotted that I would have missed! — the translucent stalks and pale sulphur-yellow sporothecae. Some of the sporothecae are topped with a drop of water, forming a unified globular shape.

They have long slender stalks and appear to have a nodding form.

The next day the stalks had turned darker — almost fuscous, but pinkish buff near the apex. The sporothecae were subglobose — maybe even lenticular — and lavender, with a darker circular zone where the stalk joined the sporothecae.

Notice the sporotheca on the right of the wood fragment, half way up, that has a lilac hue.

In the photo below taken on the 1st January 2026, the lilac sporotheca is fuscous black!

I think these sporangia are Physarum album — they seem to fit the descriptions in [1] & [2].

Nearby, another super find — a fragment of Daldinia concentrica (King Alfred's cake) ectostroma (the hard outer layer) covered with dehisced sporangia.

( Ectostroma — is that the correct term for the outer layer?? )

These sporangia have a striking dark orange-brown stalk that tapers to a slightly translucent yellowish-brown apex. They are not nodding and they don't have a petaloid dehiscence — could they be Physarum leucophaeum ?

28th December 2025

Drainage Channel Path

Near The Drainage Channel Path the daughter managed to spot some sporangia on the underside of this fallen branch.

This group appears to have a nodding form.

And this dehiscing group below has the petaloid appearance — so they are likely Physarum album.

1st February 2026

Near The Outpost

We were visiting this downed trunk frequently, observing the transformation from plasmodium to mature sporangia of Badhamia utricularis and missed the plasmodium of these sporangia below ☹️— another wonderful discovery.

We noticed that these sporangia were exactly like the sporangial cluster — likely Physarum album — on the wood fragment that we found in late December along the Drainage Channel Path.

The next day the sporothecae took on an ethereal appearance — having turned to soft shades of fawn, speckled with lime.

I think that these sporothecae are subglobose.

These sporothecae were a soft greyish violet.

The following weekend the sporothecae were dehiscing. The dehiscence was somewhat petaloid and many of the stalks were kinked — had the sporangia not been dangling, would they have taken on a nodding appearance...?

[1] The Myxomycetes of Britain and Ireland, Bruce Ing
[2] Myxomycetes – A Handbook of Slime Moulds, Steven L. Stephenson and Henry Stempen