Friday, 9 March 2018

A Sweet-grass indeed!

I've been messing about in the dirty old, smelly, manky-arsed, cow-ridden ditch that runs from the amazing Sphagnum bog, across the dirty old, smelly, manky-arsed, cow-ridden cow pastures before it disappears underground. Without wellies. Because I'm bold like that. Uh huh, yeah I am...

Here's the plant that started it all, initially found two days ago on 7th March

There's floating Glyceria leaves in the midst of that tangle of dead stems! 
Glyceria fluitans, I reckoned. Back indoors I consulted the books and realised that nothing is quite as easy as that. Transpires that there are several species (and a hybrid!) that my plant could be. Typical, I'd just have to go back and grab a handful to check. 

Which is exactly what I did yesterday afternoon. Tonight I finally got around to keying the leaves through using the awesome Veg Key. There are six potential species this could be...

First of all, leaves 10-16mm wide OR <10mm wide

Reckon that's about 4.5mm wide - which rules out Reed Sweet-grass. Five species to go...
Next the key asked for the ligule length. My whole sample had just one decent sheath, hence I only had one opportunity to check the ligule length. Ordinarily I'd like to measure a few and find an average. Was mine 1-3mm and shorter than wide OR 6-10mm and longer than wide? 

Bit bashed and torn, but c5mm and clearly longer than wide. Rules out Whorl-grass. 4 species to go...
The next feature I needed to check for was the presence or absence of cross-veins in the leaf. Whacking a leaf blade under the microscope gave a pretty categorical answer

Definitely exhibits cross-veins. That rules out Small Sweet-grass. Just 3 species to go now!
It all went a bit subjective from here on in:
Leaves 5-10(15) mm wide and yellow green, deeply ribbed, rough or smooth both sides
Leaves 5-10mm wide and dull dark green, variably ribbed, rough or smooth both sides
Leaves 4-6(10)mm wide and fresh green, shallowly ribbed, occasionally rough above

Well, my plants were ribbed but not noticeably (though I had nothing to compare them with!) In the water (check the top pic) they were definitely a pale greyish green colour. Add to that the leaf width (4.5mm) and I think we're on safe ground to say it is the latter species of the above key. And the result is.....

....Glyceria fluitans (Floating Sweet-grass) - just as I bloody well thought in the first place! But it is good practice to run things through the keys, I should do so more often, truth be told. 


But that's not all, oh dear me no sirree, it's not. I squeezed some water from my handful of Glyceria and whacked it under the compound microscope, just in case there were any microscopic things of interest. There certainly were...

A mighty fine looking freshwater alga if ever I saw one. Whatever it is...
Using Nick's copy * of The Freshwater Algal Flora of the British Isles, I narrowed this down to one of the Draparnaldia genus. Luckily, there are only two species in Britain (and they may turn out to be the same species anyway). Back to using the keys once more...

* Nick, can't thank you enough for the loan, it's an absolutely fantastic book! I'm being very careful not to crease the pages or dog ear the corners, honest mate! :)  

The shape of the cells in the primary branches are a critical difference between the two 'species'; one has barrel-shaped cells, the other cylindrical/slightly constricted at cross walls. Hmmm...let me zoom in some more and have a butchers

I think more barrel-shaped than cylindrical.
Here are the options as drawn in the book. Typically my specimen seems a bit ambiguous.

Barrel-shaped cells of Draparnaldia glomerata
Cylindrical cells of Draparnaldia mutabilis
I was still a bit undecided. My barrels seemed a bit kinda cylindrical, in a barrelesque kind of way. Luckily, I whacked a few Glyceria blades under the microscope and found plenty of epiphytic algal growth on them including this very fine specimen.

Just check out the barrels on that !!!
Seems like a very good fit for Draparnaldia glomerata to me. To quote from the Algal Flora - 

Probably cosmopolitan, widely distributed in the British Isles where it forms bright green gelatinous tufts (edit - I put my finger in it, definitely gelatinous!) commonly 5-20cm long, growing on various surfaces (eg stones, aquatic macrophytes) in a wide range of aquatic habitats including the clear, soft waters of shallow peaty pools in the Scottish Highlands...

Good enough for me! Of extra interest was this leech that I found clinging to the underside of a stone in the River Conon on 7th March. Turns out to be the rather widespread (though not recorded from Skye) Glossiphonia complanata which, despite being very common in almost any type of freshwater habitat, is a new one for me! Here it is as per when I found it

And here's the same leech in a pot

Now I know what you're all thinking. It's March. March is Lichens Month. And I really didn't do too well with February's Bryophyte Month did I? No, I didn't. Watery ditches aren't renowned for their amazing lichen diversity. So I looked at some trees 'n stuff too. 

The distinctly papillate (warty-edged) apothecia of Melanohalea exasperata - a lifer for me!

Sticta limbata - a lovely member of the Lobarion community
Sticta canariensis - another rather special lichen that's commonplace up here
Last pic, proof that Spring is here - finally! 

Music time again (I have a sneaky feeling this is the only reason a few of you even bother with this blog...) Anyway, presuming that you read all of the above and didn't just skim down here for your fix of great songs, here are tonight's toons for you. As ever, I hope you enjoy.

First up is this old skool classic, Korn's Freak on a Leech...

Followed by the massively underrated Sticta Your Guns


  1. My experience on Skye is that Glyceria fluitans is common and G. declinata rather less so. No other species or hybrid has been recorded - and that may well be the reality as I used to record other species and hybrids further south i.e. I know what they look like!

    1. That's good to know, thanks. G.declinata is my next target...

  2. And I meant to say... I quite often see leeches but I have never had the confidence to identify them. Do you fancy a leech by post some time?

    1. Now there's an offer I don't receive very often! By all means, yes.

  3. That alga is a beaut. They have that alluring geometry that bryophytes have, making a lot of a little. Remember now, 6 figure grids on all those lovely lichens! Plus you'll be at 500 by month end no problem, innit?

    1. Ermmm...hopefully! Took me until 20th April to hit 500 last year.