Friday, 6 September 2013

Calamagrostis canescens - Purple Small-reed

Grass of the Month for September  2013

It’s not often I come across a new, or relatively new grass for me.

For the quick way to key out this grass go here..

Meanwhile I’ll tell you the circuitous route I took to work it out.

“We’re going to visit a tiny patch of fen with lots of Devil’s bit Scabious,” said Craig “and it’s between some willow carr and a sand dune. You’ll like it”

It was in central Yorkshire, just east of the Derwent Ings.

To get there we bumped along under the sun, in the landrover,  along tracks past interminable arable fields, then two fields growing grass turf (to roll up and sell in strips)..

 The soil was indeed made of sand. We piled out of the landrover and saw sandy weeds: Sand Spurry (white flowers),  Stork’s-bill (pink flowers), White Campion,

Then we dropped down to this moist peaty area – and saw the patch blue with Scabious (Succisa pratensis), yellow with Tormentil (Potentilla erecta) and white with Green-veined White butterflies. Valerian and Angelica had finished flowering. Two Small Copper butterflies fluttered by (and there was Common Sorrel in the field – their larva’s food plant)

 Star sedge, Pill sedge, Common sedge, Carnation sedge, Brown sedge,
     (Carex echinata, pilulifera, nigra, panacea, disticha,)
Heath Grass, Mat grass, lots of Sweet Vernal grass, Creeping Soft-grass, Brown Bent, Common Bent, Velvet Bent
      (Danthonia decumbens, Nardus stricta, lots of Anthoxanthum odoratum, Holcus mollis,
       Agrostis vinealis, Agrostis capilaris, Agrosis canina

and Blunt-leaved Bogmoss Sphagnum palustre,.

“National Vegetation Classification categogory M26b.  (When surveying the Dales, any wet meadow that came out interesting came out to M26b – so this is what it must be - well a mixture of that and maybe U4)”

Craig had left it the area unmown to let the Scabious flower – It was 3 Sept.

Then we continued a little lower to the mown area. “What is this more yellow green grass?” he asked.

I sat down next to the 10cm long, but nevertheless mown grass. There were extensive patches of it – and when I pulled it up, a tuft of several shoots came out, not just one shoot.

Newest leaves rolled, slender blades (less than 5mm wide) and stems, shortish but not very short ligule – APPARENTLY hairless – it seemed like an Agrostis – but was too big for Agrostis capillaris. Non-descript, emerging leaf rolled – that is like an Agrostis.
Yet it did not have any of the features I might expect for other “Slightly bigger than Agrostis grasses” that might be found growing here:

  • No swollen base for Phleum
  • No orange marks and knobbly bits at the shoot base for Arrhenatherum
  • Not a fat enough shoot and dark red lower sheaths and black base for Alopecurus
  • No auricles for Elymus repens or Hordeum secalinum

Then by the fence we saw very tall uncut plants – still very slender – and the panicles narrowly spreading like rolled up plastic Christmas trees – all the tiny spikelets had fallen off – perhaps it was Agrostis gigantea – Giant Bent -

Yes that plant is an arable weed and likes to grow where there is a fence to lean on.. It’s shoots were branching half way up as does Agrostis gigantea (though the sheaths opened to let the branch out whereas Agrostis gigantea is supposed to have any side branches poking a hole through the sheath.
Further round the corner, by the ditch there were extensive beds of this.  I had never seen such dense stands of Agrostis gigantea.

Then we noticed more inflorescences – and saw that the tiny spikelets had pappuses – pappi? Of hairs – like tiny dandelion clocks.

It’s Calamagrostis! I said. (And hazy memories of having found a Calamagrostis near the Pocklington Canal 23 years earlier came back)

Not Calamagrostis stricta  (Narrow small reed)as at Malham Tarn because that has the leaves  very stiff and strongly ribbed with minute hairs on them to give a bluish effect, and a very narrow upright panicle.

Not Calamagrostis epigejos (Wood Small-reed) because that has wide leaves, almost as wide as Phalaris (Reed Canary-grass), and is a pest in woods..  mind this Calamagrostis seemed to be spreading rather extensively..

We looked it up in the book and it was Calamagrostis canescens

And guess what – it has HAIRY leaves. Agrostis’s are never hairy -  I just had not looked carefully.
Since returning home I checked it in Poland and Clement:-

Lvs rolled | Auricles Absent | blades hairy above | sheaths hairless | sheaths open and overlapping – takes us to group HQ

Then strongly narrowed at base and wet habitats.
well definitely a wet habitat – but only slightly narrowed at the base.

Then strongly rhizomatous
Yes  there are great spreading beds of it now I look round – (You don’t get Agrostis gigantea in such beds, it’s much more scattered, and the shoots emerging more individually)

Now we have to split Calamgrostis purpurea (Scandinavian Small-read) from Calamagrostis canescens – Purple Small-reed:
 Calamagrostis canescens has slightly narrower leaves – 2.5 – 6mm (not 5-7mm)  and a slenderer culm – inflorescence stem  (1.5mm diameter - not 3mm diameter). And Canescens has a ligule that is 1 (-5) mm long, cilolate, obtuse, hairy, turning brown.
Ciliolate – the end of the ligule having lots of tiny hairs like an eyelash.  –let’s examine our specimen – yes it is!

Spiders made nests in the panicles

Not forgetting the brambles in the hedgerow as we left

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