Rye-grasses & Couches
What are they?
This page covers two main groups of grasses - the rye-grasses in the genus Lolium and the couches in the genus Elymus, plus a small number of species from other genera that have a similar appearance. In general terms, these species share a similar appearance in their spikelets, which are arranged in a double row, alternating along a central axis to produce a narrow, upright spike of flowers.
Where are they found?
This group includes two of our commonest grass species (Perennial Rye-grass and Common Couch), found throughout the region in most habitats. But it also includes some more specialist species of coastal habitats and woodland, so location can at times be helpful towards identification.
Identification
Click here for help with some of the terminology used on the grass pages. There can be much variation in these species, so care needs to be taken in making an identification. In particular, the presence or absence of awns on the flowers can be very variable and should not be relied upon alone for an identification. The arrangement of the spikelets on the main stem will separate rye-grasses from the couches - spikelets with broader sides facing outwards will be a rye-grass, while couches have the broader sides facing the central axis of the stem.
Perennial Rye-grass Lolium perenne
A native perennial, abundant in most grassy habitats and commonly dominant in hard-wearing lawns in parks and sports grounds. Flowers May to August. Plants 30-80cm in height, variably tussocky or more open and with non-flowering shoots (tillers) at flowering and fruiting time as well as creeping rhizomes. Leaf blades 2-6mm wide, hairless, slightly ridged on the upper side and distinctly glossy on the underside, folded along the midrib when emerging. Leaf sheaths rounded and hairless. Ligule membranous, short. Flower spike long, narrow and wiry. Spikelets 7-20mm with 4-14 florets, alternating from one side to the other along a sinuous central stem, with the flat face of the spikelets at 90 degrees to the central stem. Lemmas blunt or pointed at the tip, but without awns.
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Italian Rye-grass Lolium multiflorum
An introduced annual or short-lived perennial, frequent in grassy habitats on roadsides and unmanaged areas. Flowers June to August. Plants 30-80cm in height, variably tussocky or more open but without non-flowering shoots (tillers) or creeping rhizomes at flowering and fruiting time. Leaf blades 2-10mm wide, hairless, slightly ridged on the upper side and distinctly glossy on the underside, inrolled along their length when emerging. Leaf sheaths rounded and hairless. Ligule membranous, short. Flower spike long, narrow and wiry. Spikelets 8-25mm with 5-15 florets, alternating from one side to the other along a sinuous central stem, with the flat face of the spikelets at 90 degrees to the central stem. Lemmas blunt or pointed at the tip, with an awn up to 10mm long.
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Common Couch Elymus repens
A native perennial, common to abundant in a wide range of disturbed and open ground, roadsides and grassy places. Flowers May to August. Plants 30-120cm in height, variably tussocky or more often forming extensive patches from far-creeping rhizomes. Plants may be green or strongly glaucous (blue-grey). Leaf blades 1.5-10mm wide, hairless, slightly ridged and variably downy on the upper side and rough on the underside, the ridges having rounded (not flat) tops. Leaf sheaths rounded and hairless on the upper leaves, downy on the lower leaves, with the sheaths of the lower leaves not having a row of minute hairs along their exposed margin. Ligule membranous, very short. Flower spike upright or drooping to one side. Spikelets 10-20mm with 3-8 florets, alternating from one side to the other along a sinuous central stem, with the flat face of the spikelets facing the central stem, like clapping hands. Lemmas blunt or pointed at the tip, with or without an awn to 15mm in length. Largely replaced in coastal habitats by Sea Couch (Elymus athericus).
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Sea Couch Elymus athericus
A native perennial, common to abundant in a wide range of coastal grassy places, especially on coastal floodbanks and at the upper limit of saltmarsh habitat, where it can form extensive monocultures. Flowers June to August. Plants 30-120cm in height, forming extensive colonies and often laid over by the weather. Plants typically strongly glaucous (blue-grey). Leaf blades 2-6mm wide, hairless, slightly ridged on the upper side, the ridges having flat (not rounded) tops. Leaf sheaths rounded and hairless on the upper leaves, downy on the lower leaves, with the sheaths of the lower leaves having a row of minute hairs along their exposed margin. Ligule membranous, very short. Flower spike upright and rather stiff. Spikelets 10-20mm with 3-10 florets, alternating from one side to the other along a sinuous central stem, with the flat face of the spikelets facing the central stem, like clapping hands. Lemmas blunt or pointed at the tip, awnless, or sometimes with an awn to 10mm in length. Best told from Common Couch (Elymus repens) by the flat-topped leaf ridges and the minute bristles on the margin of the leaf sheaths.
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Sand Couch Thinopyrum junceiforme
A native perennial, frequent in sandy, coastal habitats. Flowers June to August. Plants 20-60cm in height, forming rather open colonies of stems from creeping rhizomes. Plants typically glaucous (blue-grey). Leaf blades 2-6mm wide, hairless below, slightly ridged on the upper side, with the veins covered in minute hairs. Leaf sheaths rounded and hairless, without auricles. Ligule membranous, short and bluntly rounded. Flower spike upright or slightly arched. Spikelets 15-28mm with 3-8 florets, alternating from one side to the other along a sinuous central stem, with the flat face of the spikelets facing the central stem, like clapping hands. Lemmas 11-20mm, blunt or slightly notched at the tip with a minute spike.
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Bearded Couch Elymus caninus
A native perennial, uncommon but widely scattered in woodland and shady places, usually on chalky clay soils. Flowers June to August. Plants 30-100cm in height, loosely tufted without rhizomes. Leaf blades 4-13mm wide, hairless or slightly hairy on the upper side. Leaf sheaths rounded and hairless, without auricles. Ligule membranous, short and bluntly rounded. Flower spike upright or slightly arched. Spikelets 10-20mm with 2-6 florets, alternating from one side to the other along a sinuous central stem, with the flat face of the spikelets facing the central stem, like clapping hands. Lemmas 8-13mm, narrowed at the tip into an awn up to 20mm long (though sometimes awnless).
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Lyme-grass Leymus arenarius
A native perennial, favouring sand dunes but also quite widespread on shingle and occasionally on low sea cliffs. Flowers July to August. Robust plants, growing to 150cm (sometimes more) in height, forming spreading clumps. Plants strongly glaucous (blue-grey). Leaf blades 8-20mm wide, ridged on the upper side, the ridges slightly rough. Leaf sheaths rounded and hairless. Ligule stiffly membranous, very short. Flower spike upright and rather stiff, 15-35cm in length. Spikelets 20-32mm with 3-6 florets, usually joined in pairs. Lemmas tough, pointed at the tip, awnless.
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