Perennial Ryegrass

Lolium perenne L.

Family: - Poaceae.


Lolium is from the Greek word for craft, deceitful or treacherous because Darnel (Lolium temulentum) can be toxic and it was believed to be a changed form of wheat.

Perennial Ryegrass.

Other names:

Ray grass



A palatable, hairless, winter growing perennial grass with awnless spikelets with a short lower husk and leaves folded flat in the bud.





Folded lengthwise and flat in the bud.

Blade - Soft, bright green, 30-200 mm long by 2-6 mm wide, parallel sided, flat or folded, glossy and smooth on the underside, smooth or slightly rough on the upper side. Finely striped on the top when green and on both sides when dry. Hairless. Pointed or blunt tip.

Ligule - short, membranous, 1-2.5 mm long, flat topped.

Auricles - Yes.

Sheath - Hairless, smooth, split to the base, rounded on the back.


Loosely to densely tufted, slender, smooth, usually erect, 80-900 mm tall. Hairless. 2-4 nodes. Also has barren leafy shoots to 500 mm which form a dense sward when grazed.

Flower head:

Slender, stiff, spike, 40-300 mm long, green or purplish, straight or slightly curved. Smooth or rough on the edges. 5-35 spikelets alternate on opposite sides causing the stem to zig zag.


Spikelets - 5-23 mm long, oblong to oval, flattened, stalkless, lying in concave recesses in the stem. Awnless. Top spikelet has both glumes. Spikelet has 2-14 florets sometimes with 1 or 2 empty ones. Stands out from the stem at maturity.

Florets - Bisexual, lance shaped to oblong. Protrude well beyond the outer glume or husk.

Glumes - Egg shaped, 3.5-15mm long, 3-9 ribs, back rounded. First glume is only present on the terminal spikelet. Second glume is 3-9 nerved and about half the length of the spikelet.

Palea - Similar to lemma or 1 mm shorter. Keels with very fine teeth.

Lemma - Oblong to egg shaped, 3.5-9 mm long, 3-5 ribs. Usually awnless. Occasionally has an awn underneath up to 8 mm long.

Stamens -

Anthers -

Breaks above the glumes and between the florets.


Oval grain enclosed in palea and lemma.


Oval to cylindrical grain. Yellow-brown to grey and striped. Surface grooved, ridged and hairless.



Key Characters:

Florets lance shaped, not swollen in fruit. Lemmas awnless. Outer glume is about half the length of the spikelet. Leaves are folded flat in the bud. Grain linear-oblong.


Life cycle:

Biennial or short-lived perennial. Seeds germinate in autumn and winter. It grows over winter and spring producing many tillers and leaves. Flowering stems emerge in spring and it flowers September to December. It may become semi dormant over the dry summer period and recommence growth in autumn from the perennial crowns.


Rust susceptible.

Doesn't persist under hot dry conditions.

Less productive during cool periods.


By seed.

Flowering times:

Spring to summer in western NSW.

September to January in SA. Occasionally in May.

September to December in Perth.

Spring and summer in WA.

Seed Biology and Germination:

Vegetative Propagules:



Forms hybrids, especially with Italian Ryegrass (Lolium multiflorum) and Annual Ryegrass (Lolium rigidum).

There are many cultivars and at least 6 are commercially available such as Grasslands Ruanui, Tasmanian No. 1, Kangaroo Valley, Victorian, Medea and Tasdale.


Population Dynamics and Dispersal:

Requires an annual rainfall greater than 550 mm and a growing season more than 8 months to persist.

Origin and History:

Mediterranean. Europe. North Africa. Asia.





Temperate. Cooler areas with high rainfall.


Plant Associations:



Fodder, hay and lawn grass.

Irrigated and dry land pasture grass.

Good winter and prolific spring feed producer. One of the most valuable introduced pasture grasses.


Weed of rotation crops, perennial crops, grassland, roadsides, pastures and disturbed areas.


Toxic. Can cause ryegrass staggers. This usually occurs with flushes of growth in autumn or spring especially on short grazed dried grass with little leaf or after a hay cut. Most likely in March to April and again in January. Sheep, especially young ones and to a lesser extent cattle and horses are affected. It is rarely fatal.

Also causes facial eczema, which can be fatal. This usually occurs when a hot dry summer is followed by a mild autumn with high night temperatures, humid days and occasional rain.

Both conditions are due to an associated fungus rather than the plant itself.

It may also accumulate toxic quantities of nitrate.

Pollen from spring to summer may cause asthma and hay fever in people.


Staggers - tetanic spasms, head shaking, incoordination, staggering gait, and collapse. In spasm their legs go straight out, the head back, arched back and the eyes are rolled back and twitching. It is aggravated by an sometimes only seen after droving. Cattle tend to kneel with their noses on the ground, goose step and sway their heads. Horses appear drunk. Recovery takes a week to a month.

Facial eczema - photo-sensitisation, jaundice, head shaking, foot stamping, rubbing on fences, seek shade, swelling of the ears, eyelids, legs followed by encrustations then death of the skin, scabs then peeling to expose new skin. Ears droop with swelling then curl upwards as they dry up.


Remove stock from area.

Don't graze when rapid regrowth occurs after rain.



Management and Control:


Eradication strategies:

Graze heavily and continuously, cultivate or spray with herbicides.

Herbicide resistance:

Biological Control:

Related plants:

Annual Ryegrass (Lolium rigidum) has a glume about as long as the spikelet.

Darnel (Lolium temulentum)

Italian Ryegrass (Lolium multiflorum) has it leaves rolled in the bud rather than folded and has an awn on the lemma.

Perennial Ryegrass (Lolium perenne) has a glume about half the length of the spikelet.

Stiff Ryegrass (Lolium loliaceum)

Plants of similar appearance:

Barley grass, Brome grass, Fountain grass, Guildford grass, Quaking grass, Sand fescue, Silver grass, Volunteer cereals, Wild oats, Toad rush, Winter grass.


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