Wednesday, 30 June 2010

Briza media - Quaking Grass

Quaking grass - Briza media

Grass of the Month - June

Is Quaking grass your favourite grass?

The beautiful hanging spikelets come out in mid June and dangle and wave in the wind. Their heart shaped lemmas become dark glossy brown and sparkle in the sun. It grows in a variety of habitats but often with other very special flowers:
  • On limestone grassland with Rockrose and Ladies-mantle
  • On chalk grassland with Orchids
  • In calcareous flushes with Birds-eye Primrose
  • In slightly acid flushes with Common Spotted-orchid
  • In traditional species rich hay meadows with Wood Cranesbill or Meadow Cranesbill.

    It doesn't grow on your average lawn or ryegrass pasture/silage field
I took the picture above on 27 June 2010 at Winskill Stones Nature Reserve - see how brown and burned the grass is in the background on the shallow limestone soils with the drought. In the background are Ingleborough (left) and Pen y Ghent (right)

Here is a close-up from the picture.
It kept shaking in the wind so I put a piece next to a rock.  And now you see the rock is covered with lichen

It has many different local English names.

But how do you recognise it when it is not in flower?

With a group of a dozen students I give each student a different feature to remember:
  1. They are small plants.
  2. Small flat leaves.
  3. Hairless
  4. No auricles
  5. Blades make an almost right angles with their sheaths. The shoot is erect.
  6. Emerging leaf rolled

    The above features mean it looks like, and could be confused with other pasture grasses:-
    Common Bent, Sweet Vernal-grass, Crested Dog's-tail or even Small Cat's-tail

    So what is special? - Learn these tips to become an expert:-
  7. It has slightly wider, whiter, fleshier leaves than most of the above (apart from Small Cat's-tail)
  8. The blades spiral on their own axis (as does only Small Cat's-tail)
  9. The blades often have crimson blotches or purple polo shaped marks.
  10. They have yellow brown dead lower sheaths (as can Crested Dog's-tail)
  11. They have rhizomes 1 cm long. Hence if you have one Briza shoot, look one cm away and you should find another. Dig one up (with landowner's permission of course) and look for the rhizome.
  12. And the clinching fact? - the feature you could look for and ignore all the above?
    Hold a blade up to the light and look with a handlens:-

    You will see a striking regular pattern: (Say this:-)
    "Green, medium green;   green, dark green;  green, medium green;  green,white.    Green, medium green,  green, dark green,   green, medium green,  green,white.
    Green, medium green;   green, dark green;  green, medium green;  green,white.    Green, medium green,  green, dark green,   green, medium green,  green,white."
    Common Bent, Crested Dog's-tail and Sweet Vernal-grass have just a simple pattern: dark, light, dark, light, dark, light, dark, light.

    Small Cat's-tail - and small versions of Timothy - (which have wide white fleshy leaves which spiral on their own axes) also have a fancy pattern with some much whiter veins. But they do not have the extremely regular pattern that Briza does. (And they have swollen bases to their shoots and no rhizomes and no yellow brown old sheaths)
I hope you found this useful - Why not come on a Grass Identification course? And have fun learning about grasses with other people. J.A

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