Grasses: The Top 20
What are they?
This page serves as an introduction to grasses by presenting the 20 most common and/or widespread species that occur in East Anglia. The list is made up of species that either occur through a very wide number of habitat types (such as Common Cock's-foot and Common Bent), or which can be dominant and abundant in the places where they can be found (such as Common Reed). Learning these 20 species will help greatly towards learning grasses in general and, once you have learned the commonest species, you will more easily spot when something looks different.
Where are they found?
These species are found across all of the basic habitat types, with a number of species occurring in more than one. Some may have both natural distributions (in meadows, for example) and distributions influenced by humans (roadsides, disturbed places, gardens, parks etc.). Under each species, the typical habitat types are mentioned, as well as soil type, where relevant.
Identification
Identifying grasses successfully requires at least a basic knowledge of the plant parts and thus it's useful to know the names of these parts (it's much easier mentioning lemmas and glumes if one doesn't have to describe where they are every time!) To assist in this, you can click here to reference a page that gives details of these features. A good rule of thumb when working through the identification of any plant is to work from bottom to top with the whole plant and from outside to the middle with the flower parts (i.e. root, stem, leaf, flowers... sepal, petal, stamen, stigma) and this rule is generally followed here, though of course grass flowers have glumes, lemma, palea, stamens, stigma.
One important point to remember with grasses is that the flower spike can look very different according to how far along the process from flowering to setting seed that it is. Many species begin with a tight, rod-like cluster which opens out when in full flower and then closes back up again after pollination. Thus, it is important to look carefully at the parts of the florets (individual flowers) regardless of the shape of the overall flower spike, just to be sure. To get around this variability, botany books often write descriptions of grasses when they are said to be 'at anthesis'. This simply means at the point that the anthers open to release the pollen and this ensures that we are always looking at the flowers at the same point in their development. Grasses can still be identified outside of this point, but you need to understand that the overall spike might look different (the smaller flower parts will generally not change much, however). To simplify this a little, I have used the terms 'early flower spike/spikelets/florets' for spikes where the flowers have not yet reached anthesis; 'flowering spike' for plants at or around anthesis; 'late flower spike' for spikes where the flowers have passed anthesis and are progressing towards seed set. Where these terms are not used, you can assume that the flower spike doesn't change significantly in appearance over the course of the flowering period.
While this page contains the species that you are most likely to come across in most situations, it should be noted that most of them have look-alike, closely-related species. Therefore, it is recommended that you follow the link given for each species to the page where it will be compared in greater detail with possible confusion species, as a way of confirming your identification.
Annual Meadow-grass Poa annua
A native annual or short-lived perennial found in all types of open ground, bare patches in lawns, gravel drives, cracks in walls and pavements etc. Flowers more or less throughout the year, but especially from late November to June. Leaves hairless, pointed at the tip or slightly rounded and hooded, 1-5mm wide. Flower spike open and spreading at anthesis and remaining open at fruiting. Spikelets densely packed with 3-10 florets. Plants in dry places can be very small and compact, but more open and spreading in shady or wetter places. Compare with other meadow-grasses.
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Smooth Meadow-grass Poa pratensis
A native perennial found in many types of grassy places such as lawns, meadows and roadsides, as well as cracks in walls and pavements etc., but typically avoiding wetter places. Flowers May to July. Plants 10-80cm in height according to habitat (shorter in dry, open places, taller when among other plants or in shade) and spreading to form extensive patches. Leaf blades and sheaths hairless, pointed at the tip or slightly rounded and hooded, 2-5mm wide. Leaf ligule membranous, short. Flower spike open and spreading at anthesis and remaining open at fruiting, with 3-5 branches at the lowest node. Spikelets densely packed with 2-5 florets. Note that this is the commonest of a cluster of rather similar species and subspecies found in East Anglia. Compare with other meadow-grasses.
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Rough Meadow-grass Poa trivialis
A native perennial found in many types of grassy places such as lawns, meadows and roadsides, but especially favouring shady places and the meadow-grass most commonly occurring in woods and wetter places. Flowers June to July. Plants 20-100cm in height and spreading to form extensive patches by means of many, non-flowering shoots (tillers). Leaf blades 1.5-6mm wide, hairless, pointed at the tip. Leaf sheaths keeled, slightly rough to the touch. Leaf ligule membranous, long. Flower spike open and spreading at anthesis and remaining open at fruiting, with 3-7 branches at the lowest node. Spikelets densely packed with 2-4 florets. Typically the largest of the three common meadow-grasses. Compare with other meadow-grasses.
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Common Bent Agrostis capillaris
A native perennial found in most grassy places but especially on acid soils. Widely used as a grass for fine lawns, due to its very narrow leaves. Flowers June to August. Plants 10-70cm in height and spreading by short rhizomes to form slightly tufted patches. Leaf blades 1-5mm wide, hairless, finely pointed at the tip. Leaf sheaths rounded, smooth. Leaf ligule membranous, long. Flower spike very narrow when young, open and spreading at anthesis and remaining open at fruiting. Spikelets tiny, 2-3.5mm, clustered towards the tips of very fine branchlets with a single floret in each spikelet. Lemmas not awned. Spikelets may be green (especially in shade) but are more often purplish. Compare with other bents.
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Creeping Bent Agrostis stolonifera
A native perennial and one of the most abundant grasses in the region. Occurs as a native in all types of damp habitats and on heavier soils and is widely used as a tough, turf grass in amenity areas. Flowers July to August. Plants to 80cm in height and forming dense, creeping mats by way of leafy stolons that root from the nodes. Leaf blades 0.5-5mm wide, hairless, finely pointed at the tip, rolled when young but eventually flat. Leaf sheaths rounded, smooth. Leaf ligule membranous, medium to long. Flower spike very narrow when young, open and spreading at anthesis then closing again at fruiting. Spikelets tiny, 2-3mm, clustered towards the tips of very fine branchlets with a single floret in each spikelet. Lemmas not awned. Compare with other bents.
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Red Fescue Festuca rubra
A native perennial, abundant in all kinds of grassy places and as a lawn grass. Flowers June to August. Very variable in appearance with several subspecies recognised, especially in coastal habitats. Plants 20-100cm in height and variably spreading or clump forming. Leaf blades often very fine, 1-5mm or more wide according to subspecies, hairless, finely pointed at the tip, rolled or flat. Leaf sheaths rounded, smooth, fused together more or less to the top and hiding the minuscule ligule. Flower spike spreading at anthesis, often slightly drooping towards the tip when young. Spikelets 5-14mm with 3-12 florets. Lemmas shortly awned. Compare with other fescues.
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Tall Fescue Schedonorus arundinaceus
A native perennial, frequent to locally common on roadsides and rough, marginal land, often spreading from where originally sown as a pasture grass. Flowers June to August. Plants 45-200cm in height, often forming tough tussocks, except where regularly mown or grazed. Leaf blades tough, long strap-like, 3-12mm wide, hairless or slightly hairy beneath, tapering to a fine point. Leaf sheaths rounded, not fused together around the stem and ending in two, wing-like auricles that have a few bristles on their margins. Ligule membranous, short. Flower spike narrow when young, spreading at anthesis. Spikelets 10-18mm with 3-10 florets. Lemmas shortly awned or awnless. Compare with other fescues.
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False Oat-grass Arrhenatherum elatius
A native perennial, common to abundant in many kinds of grassy places and often forming continuous cover for many miles along main roads, hedgebanks and on coastal floodbanks and similar places. Flowers June to August. Plants 50-180cm in height, loosely tussock-forming. Leaf blades 4-10mm wide, hairless or slightly hairy beneath, flat and pointed. Leaf sheaths rounded, usually smooth but sometimes a little hairy. Ligule membranous, short, rounded at the tip. Flower spike narrow when young, spreading at anthesis and becoming very narrow and upright with age. Spikelets 7-11mm with usually 2 florets (occasionally up to 5). Lower lemma with a 10-20mm awn, upper lemma shortly awned or awnless. Compare with other oat-grasses.
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Yorkshire-fog Holcus lanatus
A native perennial, common to abundant in many kinds of grassy places and often forming large stands on roadsides, banks and rough ground. Flowers May to September. Plants 20-100cm in height, variously as spaced stems or densely tussock-forming according to land use and management. Leaf blades 3-10mm wide, softly hairy or downy, flat and pointed. Leaf sheaths rounded, hairy. Ligule membranous, short to medium. Flower spike very narrow when young and typically pinkish-purple in colour, spreading at anthesis and remaining open with age. Spikelets 4-6mm with usually 2 florets. Lemmas keeled, the lower unawned, uppers shortly awned. Compare with similar species.
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Common Cock's-foot Dactylis glomerata
A native perennial, common to abundant in many kinds of grassy places, especially roadsides and rough or neglected ground. Flowers June to September. Plants 15-140cm in height, typically densely tussock-forming. Leaf blades 2-14mm wide, greyish-green, coarse, folded at first but opening flat. Leaf sheaths strongly keeled (due to flattened stems), hairless but rough to the touch. Ligule membranous, medium to long. Flower spike consisting of one or two, well-spaced lower branches and a cluster of short branches at the top, the lower branches at right angles during anthesis and folding up with age. Spikelets 5-9mm with 2-5 florets, the spikelets tightly bunched in one-sided clusters. Lemmas tightly packed, elongated and sharp-pointed with a stiff awn.
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Barren Brome Anisantha sterilis
A native annual, or overwintering as a biennial. Common to abundant in rough, disturbed or neglected ground, especially along roadsides, tracks and in urban habitats. Flowers May to July. Plants 15-100cm in height, very variable according to growing conditions. Leaf blades 2-7mm wide, coarse and shortly hairy, the blades typically spirally twisted. Leaf sheaths rounded and hairy. Ligule membranous, long and ragged-tipped. Flower spike consisting of long, slender branches, typically arching gracefully over to one side. Spikelets 40-60mm (including the very long awns) with 4-10 florets, the spikelets carried at the ends of the long branches. Lemmas strongly overlapping at first, later more open, with a long awn 15-30mm in length. Compare with other bromes.
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Common Soft-brome Bromus hordeaceus
A native annual, or overwintering as a biennial. Common to abundant in rough, disturbed or neglected ground as well as in open swards in meadows. Flowers May to July. Plants 15-80cm in height, extremely variable according to growing conditions. Leaf blades 2-7mm wide, softly downy. Leaf sheaths rounded and hairy (often hairless on the uppermost sheaths). Ligule membranous, medium length and ragged-tipped. Flower spike upright at first, becoming more open at anthesis, then the branches closing together again later. Spikelets 12-22mm with 6-12 florets (really small plants may have just a single spikelet). Lemmas strongly overlapping, downy, with a short awn 5-10mm in length. The commonest form in a complex group of rather similar species and subspecies. Compare with other bromes.
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Wall Barley Hordeum murinum
A native annual. Common to abundant in rough, disturbed or neglected ground and especially common in urban areas on walls, cracks in pavements etc. Flowers May to August. Plants 6-60cm in height, often forming linear colonies along track sides and the foot of walls. Leaf blades 2-8mm wide, softly downy or smooth, rather limp and typically arching over. Leaf sheaths rounded, the lower ones hairy, the uppers hairless. Ligule membranous, very short and largely hidden by the winged auricles that wrap around the stem. Flower spike upright or slightly nodding, 4-12cm long. Spikelets each with a single floret, attached to each other in groups of three, the middle floret bisexual, the outer two male or sterile. Lemmas long and narrow, with a long awn 10-50mm in length. Compare with other barleys.
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Perennial Rye-grass Lolium perenne
A native perennial, abundant in most grassy habitats and widely planted as a lawn grass and a fodder grass for livestock. 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. 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. Compare with other rye-grasses.
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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). Compare with other couches.
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Timothy Phleum pratense
A native perennial, common in natural and semi-natural grasslands and often included in fodder and grazing mixes. Flowers May to August. Plants 40-120cm in height, variably tussocky or forming patches. Leaf blades 3-9mm wide, hairless, rather stout. Leaf sheaths rounded and smooth. Ligule membranous, long, with a rounded tip. Flower spike narrow and upright. Spikelets 4-5mm long, each with a single floret, densely packed in the spike. The paired glumes are very distinctive and hide the lemmas and florets; they bear a comb-like line of stiff hairs along their edge and terminate in a pointed spike, 1-2mm long. Compare with other cat's-tails.
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Rat's-tail Fescue Vulpia myuros
A native annual, widespread in many kinds of open and disturbed habitats, especially on dry or sandy soils and as a weed on walls and pavements. Flowers May to July. Plants 10-70cm in height, larger plants tussocky with many stems but single- or few-stemmed in drier sites. Leaf blades 0.5-3mm wide, flat or inrolled, downy above, smooth beneath. Leaf sheaths rounded and smooth. Ligule membranous, short to medium. Flower spike narrow and gracefully upright. Spikelets 7-10mm long, with 3-7 florets, loosely spaced in the spike. Lemmas 5-7mm long with a long and slender awn to 15mm in length. Compare with other fescues.
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Sweet Vernal-grass Anthoxanthum odoratum
A native perennial, widespread and often common in many kinds of grassy places. Often particularly plentiful in old grasslands such as churchyards and well-managed meadows. Flowers April to July - one of the first grasses to flower in the spring. Plants 10-80cm in height, variably tussocky. Leaf blades 1.5-6mm wide, relatively short but otherwise variable, especially in their hairiness. Leaf sheaths rounded and variably smooth or hairy, with a 'beard' of whiskery hairs at the apex. Ligule membranous, medium to long, rounded at the tip. Flower spike narrow but relatively short, broadest in the middle and tapering to a point, 1-10cm in length. Spikelets 6-10mm with 3 florets, the central one fertile, the other two sterile. Lemmas olive-brown with short awns. Flowers with only two anthers (most grasses have three). Compare with other grasses of meadows.
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Early Hair-grass Aira praecox
A native annual, widespread on a wide range of dry and sandy or acidic soils, including on walls and dry banks; most common on acid heaths and dunes. Flowers April to June - one of the first grasses to flower in the spring. Plants 3-10cm in height, usually tussocky but sometimes solitary stems in difficult growing conditions. Leaf blades 0.3-0.5mm wide, narrow, inrolled and blunt at the tip. Leaf sheaths rounded. Ligule membranous, rounded at the tip. Flower spike compact, 0.5-5cm in length. Spikelets 2.5-4mm, each with 2 florets. Glumes relatively large, 2.5-4mm, enclosing the florets. Lemmas awned. Compare with other grasses of dry places.
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Common Reed Phragmites australis
A native perennial, common to abundant in all kinds of damp places, from roadside ditches to the margins of rivers, lakes and broads. Flowers August to October. Plants 100-300cm in height with strong, creeping rhizomes that produce dense, single-species stands. Leaf blades 10-30mm wide, grey-green, hairless, flat and long-pointed. Leaf sheaths rounded, usually smooth, strongly overlapping around the stem. Ligule a line of long, white hairs. Flower spike narrow when young, spreading before anthesis and remaining open with age; a feathery panicle containing large numbers of spikelets. Spikelets 10-16mm, long and narrow, purplish and with 2-6 florets. Lemmas awnless but finely pointed. Compare with other wetland grasses.
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