Quaking-grasses
What are they?
This is a small group of grasses that are easily recognised as a group by their very distinctive flowerheads, with the florets arranged in tight, pendulous clusters. These flower clusters dance and tremble in the breeze, giving the plants both their English and scientific names.
Where are they found?
Common Quaking-grass is a native of chalky to neutral grassland, while the other two species are not natives and most likely to occur in urban environments as garden escapes.
Identification
Click here for help with some of the terminology used on the grass pages. Quaking-grasses have a very distinctive flower structure that readily sets them apart from other grass groups. The flowerheads are pendulous on thin, wiry stems; they consist of a pair of enlarged glumes (often reddish or green and contrasting in colour with the rest of the flowerhead) above a strongly overlapping series of enlarged and deeply concave lemmas. The various species are readily told apart by the shape and size of the flowerheads, though note that all species have more pointed tips to the spikelets when young, broadening out with age as the seeds begin to form.
Common Quaking-grass Briza media
A native perennial of unimproved, dry soils, both chalky and neutral. Flowers June to August. Plants 15-75cm in height and forming loose tufts. Leaf blades 2-4mm wide, green, minutely rough on the margins, blunt at the tip. Leaf sheaths rounded, smooth. Ligule membranous, 0.5-1.5mm in length. Flower spike a very distinctive, open panicle with the spikelets clustered at the ends of very slender branches that tremble in the wind. Spikelets 4-7mm with 4-12 florets, forming rounded clusters. Glumes 2.5-3.5mm. Lemmas 3.5-4mm, rounded, deeply concave and strongly overlapping. Very distinctive amongst our native grasses.
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Greater Quaking-grass Briza maxima
An annual, introduced from southern Europe and widely grown as an ornamental garden plant and for flowering arranging. Frequently spreads in urban environments on waste ground and on walls and pavements. Flowers May to July. Plants 10-60cm in height, single-stemmed or forming loose tufts. Leaf blades 3-8mm wide, green, hairless, finely pointed at the tip. Leaf sheaths rounded, smooth. Ligule membranous, 2-5mm in length. Flower spike typically arching to one side. Spikelets 14-25mm with 7-20 florets, forming elongated clusters. Glumes 5-7mm. Lemmas 6-8mm, rounded, deeply concave and strongly overlapping. By far the commonest of the three species in urban places.
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Lesser Quaking-grass Briza minor
An annual, introduced from southern Europe (though considered possibly native in SW England), perhaps as a crop seed contaminant and/or from birdseed. Rare in East Anglia with only a hadnful of past records and never persisting. Flowers April to September. Plants 10-60cm in height, single-stemmed or forming loose tufts. Leaf blades 3-14mm wide, green, hairless, finely pointed at the tip. Leaf sheaths rounded, smooth. Ligule membranous, 3-6mm in length. Flower spike much branched. Spikelets 2.5-5mm with 4-8 florets, forming shortly triangular clusters. Glumes 2-3.5mm. Lemmas 6-8mm, rounded, deeply concave and strongly overlapping and not contrasting strongly with the lemmas (unlike the other species).
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