Tempting to say I found this rust fungus but I think it would be closer to the truth to say it found me. It all but jumped out at me while I was enjoying a cup of tea at the Holywell Tea Chalet.
It was growing on Red Valerian Centranthus ruber. I just recently purchased Ellis & Ellis's Microfungi on Land Plants so I thought I'd try my chances at identifying it.
Ellis & Ellis list just one fungus specific to Centranthus which is Ramularia centranthi. But the description didn't match my collection at all, so I turned to Google. "Rust fungus on Red Valerian" brought up a a discussion thread on www.fungi.org.uk with photographs of something very similar-looking, identified as Puccinia commutata.
I posted my photograph and this tentative identification on the BMS Facebook page and in less than 24 hours my collection had come to the attention of a mycologist specialising in this group of fungi: Nigel Stringer. It seems that Puccinia commutata is relatively new to the UK (there are fewer than 10 records on the FRDBI database, with the first being from 2009) and Nigel is keen to compare my collection against descriptions of the rust species which occur on Red Valerian on the continent.
Nigel advised that I should press my collection in an envelope or between two sheets of paper; so I have found an additional use for Ellis & Ellis as its impressive weightiness makes it ideal for this job! I shall send my collection off to Nigel in a week or so, once it's been successfully pressed, and look forward to having its identification (hopefully) confirmed.
I did have a go at observing its microscopic features myself, comparing against Malcolm Storey's images here (with thanks to the Lost & Found Fungi project for pointing me in the direction of those).
I got a spore print and found these things which look like collapsing, round orange sacs (aecidiospores?). About 4.5 - 5 microns in diameter.
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| Mature aecidiospores (?) 100x magnification. Mounted in water. |
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| Aecium squash at 100x magnification. Mounted in water. |
I thought that mass in the middle might be 'peridial cells'... whatever they are.
Here's those bits at the top left, at higher magnification.
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| Aecium squash at 400x magnification. Mounted in water. |
It's always difficult interpreting the microscopic features of fungi you've never encountered before. So would appreciate any hints as to what I'm looking at here!
Brian Douglas sent me a link to an old publication on The British Rust Fungi which is helpful for understanding the basic biology of these things. But this is very unfamiliar territory for me.
There was also some discussion over on Facebook about how Puccinia commutata differs from Endophyllum centranthi-rubri, as featured on the Plant Parasites of Europe site; and whether there's a case of over-lapping (broad vs. narrow) species concepts here. That's mycology for ya!
UPDATE 18/08/2018
My find at Holywell Tea Chalet came to the attention of Puccinia expert, Nigel Stringer - via the BMS Facebook page. Under instructions from Nigel, I preserved my collection (by pressing it between the pages of one of my weightier ID guides, for a week or so) and posted it off to Wales.
Nigel has been in communication with Brian Spooner about this collection, and notes that it is very difficult to tell Puccinia commutata from Endophyllum centranthi-rubri in the aecial stage (which is what I found). However, Nigel found that the aecial characteristics of my collection (spore dimensions, peridial cell measurements and the surface cracking of one of the 'faces' of the peridial cells) exactly match the descriptions available for P. commutata. On that basis, he has confirmed it as P. commutata. However, he went on to say that "the clincher would be finding the telial stage on the host from now on. The telial stage would be shiny black blobs mixed in with the yellow coronets ... Visible to the naked eye and may be long and narrow as well."
So folks, if you come across something that looks like this on Red Valerian - look out for some shiny black blobs! I feel a trip back to Holywell Tea Chalet coming on.
For the record
Date: 20/06/2018
Location: Holywell, Eastbourne, East Sussex
Grid reference: TV603973
Puccinia commutata confirmed by Nigel Stringer
Record entered into FRDBI 07/09/2018
Great blog as always Clare.
ReplyDeleteI shall be looking closely at the abundant Red Valerian plants that decorate all the walls around Rye in the coming week to see if your rust is spreading along the coast. It should be hard to miss.
Of botanical note, Centranthus ruber is an introduced non-native plant. It has spread very widely and rapidly along the South coastal regions and further inland. I have even seen it in the increasingly densely vegetated roadway central reservations of our county - thanks to reduction in maintenance some sections are beginning to look like nature reserves. Seaside plants like the dry salty environment.
Returning to the rust, as it has now followed its host into our country, it should find plenty of fresh leaves to land on and infest. Its rate of progress could be rapid indeed during the hot dry weeks ahead.
About the timing of this introduction, as you point out it is not mentioned in Ellis and Ellis 1985 nor in Wilson and Henderson 1966 (British Rust Fungi - the successor to Grove 1913, which again has no mention of Centranthus as host).So clearly it came in since 1985. How did it get here one wonders.
If I don't see it in Rye or Hastings I will have to head for the the tea rooms and try those Eccles Cakes.
Ted.
I have found one or other of these species in SDevon and in West Somerset Mark
ReplyDeleteIt's so striking when you find it, isn't it!
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