Teeny Tiny Tatties

Most folks that read this blog will already know what a plant gall looks like. These could be spangle galls on the underside of an oak leaf, as in the image below, Knopper Galls growing over an acorn, or the big lumpy growth sometimes found on bramble stems.

Neuropterus quercusbaccarum, plus remains of Neuroterus anthracinus on midrib

Gall of Jaapiella veronicae on Germander Speedwell bud

The gall causers in these images are insects, tiny wasps in the top pic and midges in the lower. Other gall inducing organisms include aphids, psyllids, beetles, moths, nematodes, bacteria, fungi and mites. Most of the more conspicuous galls encountered will be animal induced. Witch's Broom (aka Witches' Broom, Witches Broom and Witch's-broom) is one very obvious exception. Many of the less conspicuous galls are formed by an entirely different set of mechanisms and a few days back I encountered one such gall. 

And it's a goodun... 

Four of us headed off to Gedintailor, situated just a few miles south of Portree. I felt certain it was an area suggested as a possible future SNG venue, but nobody else remembered that, so we just bimbled about a bit seeing what we could find. Nick Hodgetts, god of bryology, had a great time finding 132 species of mosses and liverworts, bringing the Gedintailor tetrad total to a respectable 141 species. Stephen Bungard, BSBI Recorder for Skye, came away with precisely 200 species of plant, many of which were entirely new for the tetrad. Neil and I found various bits n bobs, some of which was new to us. Essentially we all had a damn fine time, even if we did get forced to backtrack across rocks through an incoming tide. Nobody nearly died, it was all good fun.

Before we had even left the parking layby, I spied several large clumps of Toad Rush growing in the roadside mud. Remembering that Toad Rush has a very rarely found gall on its roots, I duly uprooted a plant. Nothing, same as always. I decided to grab the largest Toad Rush plant present and pulled that up for inspection. Bigger root system means bigger chance of galls, right..? 

Holy shite!

That looks like a tiny potato growing on the roots!

I could hardly believe my luck, was this it??? The obvious worry is that I'd stupidly pulled up a Bulbous Rush by mistake and was merely eyeballing the bulbils. Nope, definitely Toad Rush, and this potato was down near the bottom of the roots, definitely not a bulbil! I carefully scraped off the worst of the dirt and realised there were several potatoes on the roots, some darker than others. 

Darker galls, presumably this means they are more mature?

Back indoors, I washed the roots in water and grabbed a few gall books whilst checking online too. I came across this amazing pdf a month or so back, scroll down to page 17 and see if anything looks familiar...

One potato... two potato... three potato... four!

This is Entorrhiza aschersoniana, a fungus that creates galls on the roots of Toad Rush. Related species of rush have their own host-specific species of Entorrhiza. So far as is known, in Britain this fungus only occurs on Toad Rush, though it has been found on Frog Rush and Minute Rush in Europe. So saying, before 2017 there was a single British record from Mull. Recently it has been found to be widespread in Wales (a survey found it in 31 tetrads), plus a few records from the Outer Hebrides and from Surrey too. It's possibly quite widespread, certainly its host is found across most of Britain, it just needs a bit of digging around to find it. Literally.

I haven't researched the mechanisms yet, I probably should have thought of that before I started writing this post, but I'm guessing the spores are distributed through the soil via water. Clearly they aren't windblown as are most fungal spores. Weird how one plant had the galls whilst a neighbouring plant didn't, maybe my pulling the right plant was just pot luck. Or maybe I really ought to concentrate on the largest plants from now on. 

I have a modest compound microscope, sadly lacking in any kind of a measuring graticule but it's alright for now. In truth I don't use it very often nowadays. The beetles and flies I look at tend to be large enough that I manage without it! Anyway, I knew I'd need to take a look at the spores if I intended to put the record through, so did a fungal squash and squinted through the eyepiece to see what I could see...

Hardly spectacular, I know. Sorry about that. One day I may treat myself to a SEM, but until that day arrives you'll have to make do with shite pics like these. So what can we see? Well, we can see that the spores are slightly oval rather than rounded and they are roughened across the surface. I'm sure the detail of the surface sculpturing looks phenomenal up close, sadly this is as good as it gets through my microscope. The good news is that Entorrhiza spores look exactly like this!

This is the pic from the pdf I linked above. Looks a fine match to me

I submitted it to iRecord last night. It's still awaiting review, but the automated email response made me smile

Rarely recorded. Please check full details inc microscopy if needed and consult colleagues.

So I asked Big John at reception, Annette in the kitchen and Chris Ann at housekeeping. They didn't know.  My colleagues suck. I shall ask the head chef when he gets in, he's ace at pub quizzes.