Quaking Grass

Briza maxima L.

Synonyms -

Family: - Poaceae


Briza is Greek meaning to nod or sleep and refers to the nodding spikelets.

Maxima means large and refers to the spikelets.

Other Names:

Blowfly Grass

Big Quaking Grass

Large Quaking Grass

Shaking Grass

Shell Grass

Shelly Grass


A delicate, hairless, annual grass with few stems and a finely branched structure carrying 5-10 broad drooping blowfly or shell like seed heads(spikelets) in spring. Each spikelet is 1-2.5 cm long, with 7-12 overlapping florets. It is native to the Mediterranean and a common weed of bushland that flowers in spring and early summer.




First leaves:


Often only a few leaves. Alternate. Green. Leaves rolled in the bud.
Blade - 40-200 mm long by 3-8mm wide, green turning red at senescence, smooth, flat, drooping with age. Mid rib prominent. Edges parallel sided, slightly roughened. Tip finely pointed. Hairless.
Ligule - Membranous, 2-5 mm long, blunt tip.
Auricles - None
Sheath - Smooth, open near top, loose. Rolled and overlapping. Hairless.


Erect, smooth, round, unbranched, 100-600 mm tall, 2-3 mm diameter, single or 2-3 arising from the base. 2-4 nodes.

Flower head:

20-100 mm long, loosely branched, nodding, one-sided, oblong panicle with 3-15 drooping spikelets. 1-3 spikelets per branch on very fine stalks (pedicels) that are 6-22 mm long.


Spikelets rattle in the wind when dry.
Spikelets - Solitary, 7-20 flowered, 10-25 mm long by 8-15 mm wide, egg shaped, shell like. Initially pale green, developing a red-brown top then turning straw-yellow or silvery. Initially succulent and becoming papery at maturity.
Florets - Usually pale, deeply hollowed, closely overlapping, about as long as wide, bisexual
Glumes - 2. Boat shaped (concave orbicular), dark brown to purplish, 7-9 ribbed, persistent. Lower glume 5-6.5 mm long. Upper glume 7-8.5 mm long.
Palea - Small, 3-4 mm long, winged, translucent. Deep set in base of lemma. Wings densely fringed on the edges
Lemma - 6-8 mm long, broadly egg shaped, 7-9 ribbed, pale, clasping at base, concave, membranous, several nerved, closely overlapping. Upper ones furry hairy.
Stamens - 3
Anthers -


Light brown, flattened, concave, 2-3 mm long. Tightly embraced by the hardened portions of the lemma and the palea .


Fibrous, short and shallow.

Key Characters:

Plant less than 600 mm tall.

Ligule membranous.

Inflorescence a panicle.

Rachilla fractures above the glumes. (Spikelet does not fall entire)

Spikelets 10-20 mm long, usually fewer than 10, drooping and quivering, 7-20 flowered, laterally compressed, all alike.

Glumes 7-9 ribbed, awnless, almost orbicular and concave on the back, shorter than the adjacent lemma.

Lemmas rounded on the back, entire, awnless, 5 or more nerved, cordate at the base, as broad as long, closely overlapping.

Adapted from John Black, Nancy Burbidge, Terry Macfarlane, Gwen Harden and Charles Gardner.


Life cycle:

Seed germinate in autumn following rain and grow slowly over winter followed by rapid growth leading to flowering in spring to summer. They die off with the onset of summer drought.


Tolerates frost.
Grows in shady situations in lower rainfall zones and in both shade and full sun in high rainfall areas.
Drought soon after germination may lead to heavy seedling losses.


By seed.

Flowering times:

Late winter to spring in western NSW.

August to December in SE Australia.

August to December in SA.

September and October in Perth.

September and October in WA.

Seed Biology and Germination:

Some seed can remain dormant for a 3 years, however most germinates in the season after production.

110 - 180 seeds m-2 have been recorded in the soil after the first flush of germination (Raynor, 1989; Molnar et al, 1989).

Seed passes through grazing animals.

There is often a strong flush of seedlings after autumn burning.

It will germinate in litter as well as on bare soil.

Approximately 85% of the seed is in the litter layer in bushland situations.

Vegetative Propagules:



Population Dynamics and Dispersal:

Spread by seed dispersed by water, wind, adherence to animals, clothing and machinery (especially mowers and slashers) and in hay or disposal of garden refuse. It is also passed in the faeces of grazing animals.

Large populations can develop quickly in areas that have been bared or burnt in autumn.

Origin and History:




New Zealand, United Kingdom, South Africa, North and South America, Lord Howe Island.

WA - Avon wheatbelt, Esperance plains, Geraldton sandplain, Jarrah forest, Mallee, Swan coastal plain, Warren



Mainly in the 400-700 mm annual rainfall zone.


Found on sands, loam and clays.

Plant Associations:



Ornamental used in dried flower arrangements.

Fodder, palatable but poorly productive.

Kangaroos eat the flower heads.


Invasive weed of coastal vegetation, grassland, heathland, woodland, sclerophyll forest, riparian areas, rocky outcrops, roadsides and gardens.

Minor weed of agriculture.

Heavy infestations reduce species diversity.

Often displaces orchids in bushland.

Increases fire risk.


None recorded.



Management and Control:

Quaking Grass is often associated with highly degraded areas and restoration often achieves control.

Grazing or cultivation provides good control in agricultural areas.

Fire can be used effectively if it is timed just as the plants die in late spring to early summer. A fire intensity of 500-700 kW/m2 (a cool burn) is required and this will also control seed in the litter.64


200 plants/m2 or 50% ground cover can reduce flora diversity by 75% in grassy woodlands. Less than 50 plants/m2 or 10% ground cover had little effect (Carr et al, 1988).

Eradication strategies:

Prevent seed set for 3-4 years by hand weeding, mowing, cultivation or herbicides. Close mowing or scorching with a gas burner before flowering in spring and repeated if necessary usually provides good control. Swards with immature seed heads can be mown with a catcher in spring. Don't mow stands with ripe seed as this causes dispersal of the very fine seed. Mowing very close to the ground usually prevents regrowth.

Flowering and seed set are synchronised in late spring to early summer which makes seed set control easier. However, this must be repeated for a number of years to deplete the seed bank in the soil.

A cool burn in late spring to early summer provides reasonable control.

Manual removal is effective for light infestations. Bag and burn plants that have seed.

10 kg/ha 2,2-DPA applied in winter, glyphosate at 2 L/ha applied in winter or spring before flowering or 40 g/ha Achieve applied when the grass has 2-8 leaves in winter provides good control. Repeat annually or if a new emergence occurs for 3-4 years.

For spot spraying, 10 mL glyphosate(450g/L) (or 200 g Propon® plus 25 mL wetting agent) in 10 L water in late winter to early spring before flowering provides good control. Propon® is preferred for early season use because it has some residual action. Most native plants will tolerate these herbicides but higher rates may cause damage.

For highly selective control use 4 g Achieve® plus 10 mL Supercharge® oil per 10 L water and apply between the two leaf and tillering stage of the grass in winter.

Herbicide resistance:

None reported.

Biological Control:


Related plants:

Perennial Quaking Grass (Briza media) is naturalised in NZ.

Shivery Grass (Briza minor) is more delicate with smaller spikelets, up to 0.5 cm long with 4-7 overlapping florets.

Briza rufa is naturalised in NZ.

Briza subaristata is perennial, has a denser flower head, shorter pedicels and tends to be one sided towards the base. It is naturalised in NSW.

Plants of similar appearance:



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