IRISH PLANT MONITORING SCHEME – IDENTIFYING GRASSES
This pdf guide introduces you to the most common grasses you will encounter
when surveying grassland plots as part of the Irish Plant Monitoring Scheme.
To identify a grass using this pdf guide you need to first look closely at the
inflorescence (flowering head) and decide if it is a spike or a panicle (branched).
In some grasses the inflorescence will be one-sided. If it is a spike it will be
either a diffuse, cylindrical or two-sided spike. If it is a panicle you will need to
look closely at the structure of the spikelets which make up the inflorescence.
For full details on identifying grasses in Ireland you should consult this
guide which was published by the Data Centre in 2015. The structure
of this pdf guide is similar to the structure used in that publication.
Your grass inflorescence will either be a spike or a panicle, and is made up of spikelets. In
some grasses it will be one-sided.
Spikelet structure
When the inflorescence is a
panicle you will need to look
closely at the spikelets. The most
important things to check for are:
Is it a one-flowered or multiflowered spikelet?
Is the glume longer or shorter than
the lemma?
Inflorescence one-sided
It can be a one-sided panicle or a one-sided spike.
In these grasses all spikelets occur on one side. You
should rotate the inflorescence fully to determine
if it is one-sided or not
Cock’s-foot - Dactylis glomerata
 Very common & distinctive grass
 Dense clusters of green or purple-tinged
spikelets in a one-sided panicle
 Hairless
 Flat leaves with rough edges
Mat-grass - Nardus stricta
 Occurs on peat soils
 Stiff rod-shaped one-sided inflorescence
 Very slender purple-blackish spikelets, 1flowered
 Narrow bristle-like leaves
Crested Dog’s-tail
Cynosurus cristatus
 Flattened dense spike
 Spikelets in groups of 2 or 3
on one side
 Short narrow leaves, glossy
below
Inflorescence a diffuse spike
Sweet Vernal Grass
Anthoxanthum odoratum


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Loosely tufted grass
Spikelet 3-flowered, lower 2 sterile
Short, flat, pointed leaves
Sweet scented when crushed or dried
* This pdf guide includes only the most common species you are likely to see within each subdivision
Inflorescence a cylindrical spike
Phleum: Inflorescence stiff. Glumes with an awn, lemma
awnless.
Alopecurus: Inflorescence soft/silky. Glumes awnless, lemma
with a long awn.
Timothy - Phleum pratense
 Inflorescence 6-15cm or longer
 Leaves 2-4(10)mm wide and up to 45cm long (lower leaves)
Marsh Foxtail - Alopecurus geniculatus
 Inflorescence up to 7cm long
 Long blunt ligule, 2-5mm long
 Stems often bending upwards at the nodes. Often has creeping
stolons.
Meadow Foxtail- Alopecurus pratensis
 Inflorescence up to 13cm long.
 Very short, flat-tipped ligule, 1-2.5mm long.
 Upright stems. Stolons absent.
Inflorescence a two-sided spike
Perennial Rye-grass
Lolium perenne
 Very common grass
 Leaves & sheaths hairless
 Sheath base wine-red in colour
Inflorescence a panicle – one fertile floret per spikelet
Velvet Bent - Agrostis canina sens. lat.
 Panicle ovate in shape
 Lemma with an awn
 Leaves narrow
 Spreads by obvious creeping stolons
Common Bent - Agrostis capillaris
 Panicle diffuse and pyramidal in shape
 Lemma with no awn
 Leaves flat
 Spreads by rhizomes, sometimes stolons
Creeping Bent - Agrostis stolonifera
 Panicles dense and linear in shape
 Lemma with no awn or very short
 Leaves flat
 Spreads by obvious creeping stolons
* This pdf guide includes only the most common species you are likely to see within each subdivision
Inflorescence a panicle – more than one fertile
floret per spikelet & glume longer than lowest
lemma
Heath-grass – Danthonia decumbens
 Narrow, compact panicle with 3-6
green or purplish spikelets
 Flower heads don’t usually open &
are rock hard
 Lemma awnless
 Leaves hairy
Crested Hair-grass – Koeleria macrantha
 Tufted, downy grass
 Short-stalked, 2-3 flowered, purplish or
greenish-white spikelets
 Glumes with silvery margins
 Lemma awnless
 Leaves can be bristle-like
Yorkshire-fog – Holcus lanatus
 Spikelets numerous, 2-flowered
 Glumes hairy
 Upper lemma with a very short delicate awn
 Stems and leaves with a velvety feel, fine soft
hairs.
 Sheaths purple striped at base (‘striped
pyjamas’)
Tufted Hair-grass – Deschampsia cespitosa
 Forms large tussocks
 Panicles loose and nodding, up to 50cm long
 Awns not clearly visible
 Leaves flat (2-5mm wide) and prominently
ribbed and rough on upper side
Downy Oat-grass – Avenula pubescens
 Tufted grass
 Spikelets 2-3 flowered
 Long silky hairs emerge from spikelet
 Lemma with long, dark brown, bent awn
(>10mm) arising from the back
 Basal leaves flat and downy
* This pdf guide includes only the most common species you are likely to see within each subdivision
Inflorescence a panicle – more than one fertile floret
per spikelet & glume shorter than lowest lemma
Quaking-grass – Briza media
 Distinctive grass
 Graceful branched panicle with shortoval spikelets on slender stalks
 Spikelets many-flowered, green or
purplish
Purple Moor-grass – Molinia caerulea
 Forms dense tussocks in wet peaty
habitats
 Panicle long and branched, with
numerous mostly purple spikelets
 Leaves flat & hairless, sometimes
sparsely covered with long hairs
Floating Sweet-grass – Glyceria fluitans
 Aquatic
 Spikelets flattened 18-35mm long,
6-14 flowered
 Stems flattened
 Leaves hairless
False Oat-grass – Arrhenatherum elatius
 *Glume is just shorter than the lowest
lemma
 Spikelets 2-flowered
 Leaves broad and flat (4-10mm wide)
 Lower lemmas with long awns (>10mm),
usually bent
 Usually hairless grass but can be variable
 Stems can be hairy at the nodes
* This pdf guide includes only the most common species you are likely to see within each subdivision
Inflorescence a panicle – more than one fertile floret per
spikelet & glume shorter than lowest lemma
Poa has flattened spikelets, no awns and hairless leaves
with boat-shaped tips that cannot be flattened without
splitting.
Annual Meadow-grass - Poa annua
 Ligule short and pointed, 1-4mm long
 Leaves often transversely wrinkled
 Generally a smaller plant
Rough Meadow-grass - Poa trivialis
 Ligule long and pointed, up to 7mm long on
flowering stems
 Leaves taper like a long isosceles triangle
Smooth Meadow-grass - Poa pratensis sens. lat.
 Ligule short and blunt, 1-3mm long
 Leaves parallel-sided (do not taper to point until
the very tip), tend to be slightly blue-green in
colour
Festuca has branched, spreading panicles. Spikelets are
held rigidly. Leaves hairless, often bristle-like.
Red Fescue agg. - Festuca rubra agg.
 Very variable widespread grass
 Spikelets reddish-green
 Lemma with short awn (<3mm)
 Lower leaves bristle like, upper leaves flat
Sheep’s Fescue agg. - Festuca ovina agg.
 Occurs in heaths, mountainous areas
 Spikelets reddish-green
 Lemma with short awn (<1.5mm)
 All leaves bristle-like, most leaves on plant <10cm
long
 Strongly tufted
Schedonorus has branched, spreading panicles. Spikelets
are held rigidly. Leaves hairless. Like Festuca but larger
and more robust and has distinct auricles.
Tall Fescue - Schedonorus arundinaceus
 Lemma sometimes with short awn or absent
 Small auricles fringed with minute hairs
 Leaves dull green, rough on underside, especially at
the edges
Meadow Fescue - Schedonorus pratensis
 Lemma without an awn
 Auricles small, fine pointed, not hairy
 Leaves bright green, glossy and smooth beneath
* This pdf guide includes only the most common species you are likely to see within each subdivision