Badhamia utricularis plasmodium to sporangia at Strumpshaw Fen – Winter 2025/26

The downed trunk on which we have seen a number of wonderful slime mould displays – Badhamia utricularis sporangia and likely plasmodia, and Heterotrichia obvelata – continues to produce super slime mould activity.

21st December 2025

Every visit to the reserve we check out this trunk – the previous day there had been no signs of slime moulds, but today there was a curry-yellow plasmodium growing over, and presumedly consuming some Phlebia radiata [1] – this was likely a Badhamia utricularis plasmodium.

The plasmodium looks as if it’s sporulating, but this is due to it spreading over the highly textured, nodular morphology of the Phlebia radiate.

22nd December 2025

The next day the plasmodium had spread leftwards consuming more Phlebia.

23rd December 2025

On the third day the plasmodium seemed somewhat diminished, almost as if it had taken what it could from Phlebia. But below it, on the bare wood, there was some plasmodial vein-like networking – the slime mould was searching for more food!

28th December 2025

Five days later a phaneroplasmodium (orange arrow) was fanning out to the right of where we saw the plasmodium five days earlier (green arrow), moving right and downwards towards a larger area of Phlebia (lavender arrow).

1st January 2026

Fours days later the plasmodium had reached the Phlebia moving rightwards across the fungus.

18th January 2026

We next visited the reserve nearly three weeks later and wow 🤯 – the plasmodium had engulfed large areas of the Phlebia leaving slimy digested fungus in it’s wake.

I can’t recall why we didn’t visit the reserve the next day – at this stage we would not have wanted to miss this plasmodium sporulate. The next visit a week later was wonderful…

25th January 2026

The Phlebia appeared to be mostly digested and in it’s place was one of the largest sporulations we had seen for some time.

In the photo below, you can see a range of development from emerging primordia (the tiny blebs) to the elongated primordia with developing globular tips, which will eventually become the sporothecae.

The next photo shows elongated primordia beginning to cluster together.

These clusters will eventually form the distinctive ‘bunches of grapes’ for which Badhamia utricularis is known, as you can see more clearly in the photo below.

26th January 2026

There was no debate – we had to come back the next day and we were not disappointed. The sporothecae had fully developed into cream, buff-yellow and orange-yellow globular clusters of globular sporothecae, hanging from a tangle of slender thread-like stalks.

Notice the speckled irridescence.

1st February 2026

Two days later the sporothecae had turned bluish-grey

The sporothecae in the centre of the photo below appear to have a liquid coating making them glossy – almost black, with a droplet of deep-olive liquid hanging at the bottom.

8th February 2026

Two days later the sporothecae were dehiscing.

I think this is the only time we’ve observed a slime mould’s life cycle from active plasmodium to sporulation, to young and mature sporangia, and to dehiscence – all in one place!

References:

[1] Bruce Ing – Tansley Review No. 62, The phytosociology of myxomycetes, New Phytologist – Page 187