Monday, 28 February 2011

Festuca ovina - Sheep's Fescue

Festuca ovina on traffic island
at north end of Settle Bypass in September
Grass of the Month for February

Why Festuca ovina for February?
Because it is  (with experience)  an easy grass to identify when it does not have flowers. For winter I am sticking to grasses that are easy to identify vegetatively - to the grasses which have needle-like leaves.

Red Fescue ( Festuca rubra ) (January's grass) and Sheep's fescue (Festuca ovina) (this month's grass) have no, or virtually no, ligule.

This distinguishes them for other needle-like grasses - Mat grass and Wavy hair-grass,( and for those people who live in the south west, Bristle Bent) which all have ligules. (There is another grass Fine-leaved Sheep's Fescue with no ligule, but that is relatively uncommon so I'll leave that for now)

So how do we distinguish Red and Sheep's Fescue?

1. Habitat
Sheep's Fescue grows in very stressful situations- nutrient poor situations where other species cannot grow.  I had wanted to include here a photo from a romantic place like a limestone pavement (basic rock) or a slate quarry (acid rock) or a peat bog or heathery heath (very acid soil). But I find the only good photo I have is of the dry traffic island at the north end of Settle Bypass, where I go to look for Compressed Meadow-grass. Here the sheep's Fescue has grown into a big tuft on the limestone pebbles and cement.

In comparison, Red Fescue grows in slightly stressful to average places with slightly low nutrients.

2. Leaf-blade just below flowerhead - Is it flat or needlelike? 
In Sheep's Fescue all the blades are needle-like, including the one just below the flower-head. Whereas in Red Fescue the blades under the flower-head are wider and can be flattened.

3. Tufted or spreading?
Sheep's Fescue is always tufted; Red Fescue usually has rhizomes and is spreading, /
though some tufted subspecies do exist.

Festuca ovina Always tufted
Festua rubra: Tufted or a plant with spreading rhizome

4. Sheaths overlapping or tubular?
Festuca ovina sheaths are Open and Overlapping - whereas Festuca rubra sheaths are tubular- they may Rip

Festuca ovina sheaths are
Overlapping or Open -
they are thus wider
than Festuca rubra
Festuca rubra sheaths are Tubular
(pronounced tooboola to rhyme with rubra),
they are thus narrower than Festuca ovina

Festuca ovina sheaths can open so there is enough space for new shoot to grow inside the leaf. (Called intravaginal branching)  In Festuca rubra there is not enough space,so the shoot makes a hole in the leaf sheath and grows through it. (Extravaginal branching) (Vagina is Latin for sheath or scabbard)
Festuca ovina sheaths can open
so there is enough space for
the new shoot to grow inside the leaf.
 In Festuca rubra there is not enough space,
so the shoot makes a hole
 in the leaf sheath and grows through it.

Weardale Mountain Pansies (Viola lutea), Pleurozium schreberi on slightly acid soil,
nutrient poor soil and a little Festuca ovina in May

Gentiana verna on Limestone in the Burren and a little Festuca ovina in May

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