Legends from an Elm branch

Guest author: Nick Aplin

A post about Elm trees, bryo-parasites, cannibalistic fungi, new species and the joys of microecology...

One of the problems with recording fungi is that the bloomin’ things are everywhere.
   Seriously, everywhere. They’re in your fridge. They’re on every single leaf. They’re even in your lungs whilst you’re reading this. Considering their ubiquity, surveying a whole piece of woodland can be somewhat daunting for the average mycologist. Where should one start?
   I think the best thing to do is earmark a microhabitat or two; perhaps an old stump, a muddy ditch or maybe a little mossy patch. Around Picketts Wood there are thankfully many such nooks and crannies: A fallen Pine trunk here, a dead hedge there...

Late last year I stumbled upon a little stand of Elm trees, presumably struggling in their war against Ophiostoma novo-ulmi, a nasty fungus which is to blame for the fact we generally doesn’t see Elms around much anymore (Dutch Elm Disease has so far claimed the lives of about 100 million Elm trees in the Northern Hemisphere).
   These trees at Picketts Wood are a bit sad looking, with many droopy dead bits. Luckily the decomposing branches are home to lots of other organisms, including some curious little fungi. To give you a snapshot of the sheer omnipresence and diversity of the fungus kingdom, I’d like to tell you about some of the many species I found on just one Elm branch over the last few weeks:

The first two species are largely dependent on dead Elm wood for survival – I wonder whether they will both be in decline considering the effects of Dutch Elm Disease?

Orbilia comma

Orbilia comma, with its little spores that look like commas.
 (OK you have to squint a bit whilst using your imagination….)

Quaternaria dissepta

A cross section of Quaternaria dissepta, its ominous, black fruitbodies embedded in the substrate and its dark, curved spores. If Darth Vader were a fungus, I reckon he’d be this one.

Bionectria ralfsii

Some scaly fruitbodies of Bionectria ralfsii breaking through the bark. This species usually comes with two types of spore: hyaline, sexually produced ascospores (right) along with green, lemon-shaped asexual spores called conidia (left).  Yes, fungi have sex too – Gross, right?

Cryptodiscus (Karstenia) rhopaloides

Karstenia rhopaloides likes to break through the bark of dead branches and is surprisingly common on many different woody plants throughout the colder months. Officially, this species is known as Cryptodiscus rhopaloides, but I guess no one has had the time to move it to the right genus yet….
Can you spot it in the branch photo above?

Diaporthe eres

A cross section of Diaporthe eres - Here, the spores are created in chambers below the surface of the substrate and are then ejected through those long creepy looking black tubes.

Hyalorbila erythrostigma

Hyalorbilia erythrostigma -These little guys are found eating other fungi. Sometimes they like to parasitize Orbilia species (see O.comma above). This little group were growing near lots of other fungi too, so I wasn’t quite sure what they were up to here!  There are only 3 previous UK records for this species.

I have no idea what to call this one. I don’t even think it has a name, yet. I know that some mycologists are aware of its existence, but they don’t know what to call it either. Perhaps it’s a Lasionectria, perhaps something else entirely. Answers on a postcard….
   Isn’t it strange to think that there are undescribed species around Gatwick?

Octospora affinis

Finally, this is Octospora affinis, a bryoparasite. It has a rather boring diet. It only eats Orthothichum affine (the moss that you can see growing on the branch above – Thanks to Brad Scott for the ID). This collection on our Elm branch is the first time it’s been seen in the UK. Perhaps it occurs elsewhere; I can’t imagine many people out there are looking for it….
   I should say that I have no idea what species of Elm I've been looking at. Elm taxonomy eludes me. If you happen to find an Elm expert (Pteleologist!) hanging around Gatwick, please point them in my direction!

Nick Aplin (Sussex Fungi Group)