Saturday, 18 August 2012

Poa compressa - Flattened Meadow-grass

Grass of the Month for August 2012

Poa compressa is rare around Settle. Settle is more or less in the centre of mainland Britain so you see we are getting to the northern edge of its distribution.

Around here it grows on very thin limestone soil... in fact on almost bare ground.

The shoots are much more compressed than the common Poa trivialis and Poa pratensis. It has short rhizomes/trailing shoots- though as it grows on bare rock they cannot grow under ground.  the first internode grows almost horizontally then the next one at an angle - in fact the whole shoot is often at an angle.  It forms thin tufts.. As it is growng on bare rock such a substratum cannot support a dense tuft.

The head is small and compact compared to P trivialis and P pratensis.. and flattened.

The rest of this post rambles on about all the places I have found this rather inconsequential small ting grass.   (Go  to the index for other grasses if you'd rather..  or will you die of curiosity if you don't read where I've found it.?)

I was first shown it on the gravel near Settle Railway Station over 30 years ago, but that land got built on or tarmacked over and the flower beds covered with woodchip.

Sometimes we used to find it (20 years ago) on the limestone in the quarried area adjacent to the

obelisk at Gait Barrows Reserve.

I saw it on a deserted railway between Skipton and Colne 20 years ago.

I saw it on a wall beside a track leading north of Stainforth down to the river.

(Isn't it amazing that such a small, often dried up plant can have so much space devoted to it!)

For the past ten years till two years ago I took my students to see it on the traffic island at the junction of the north end of Settle Bypass.




But it hasn't been there the last two years - maybe it got too dry. Or the herbicide finally killed it off.

However, during Open Gardens last year I discovered a patch on someone's drive in Stainforth.


I went back and photographed it this April . Much of it was very dead - you could see the prostrate mat of last years shoots. But new shoots were coming through

See it does like growing on stony ground

(See other months' grasses)

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