Paradoxa grass

Phalaris paradoxa L.

Family: - Poaceae.


Phalaris is the Greek for coot with its bald white head or from phalaros meaning white crested. Both refer to the appearance of the seed head.

Paradoxa grass.

Other names:

Bristle Spiked Canary Grass

Hood Canary Grass

Paradoxical Canary Grass


A tufted, erect, hairless, annual grass with rough leaves and 2-9 cm, oblong, dense seed heads just protruding from the top leaf and with spikelets falling in groups of 6-7.





Emerging leaf rolled in the bud.

Blade - Flat, 100-200 mm long by 2-9 mm wide, rough. Tapering to a pointed tip. Sometimes with a slight waxy bloom. Surface hairless.

Ligule - Thin, membranous, 3-5 mm long, rounded to flat on top.

Auricles - None.

Sheath - Striped, roughened.

Collar - Sometimes lighter in colour.


Tufted, 200-1000 mm, but usually less than 500 mm tall, erect or sometimes kneed near the base, few to many, slender to moderately stout, branched or unbranched. Hairless.

Flower head:

Dense, erect, spike like panicle, oblong to narrowly egg shaped, rarely cylindrical, narrowed at the base, 20-90 mm long by 20 mm diameter. Spikelets on tiny, rough branches surrounding the main stem. Panicle held close to or partially enclosed in the top leaf.


Spikelets - In groups of 7 (rarely 6) with 6 (rarely 5) stalked sterile ones around a single stalkless bisexual one that is broader and longer than the sterile ones. 2 of the sterile spikelets usually bigger than the others but all shorter or narrower than the fertile spikelet. Stalk(peduncle) holding group of 7 is rough. Stalk(pedicel) of sterile spikelets hairless and smooth. Sterile spikelets empty or with abortive anther.

Florets - 3, 2 are empty 1 is fertile.

Glumes - 3-9 mm long and variable in sterile spikelet. On fertile spikelet, glumes are 5.5-9 mm long by 1 mm wide, firm with up to 7 conspicuous ribs, pointed to awl shaped tip, short awn, with sickle shaped tooth like wing near or above the middle of the keel. Edges not membranous.

Palea - Pale at maturity. Hairless. Shining.

Lemma - Of empty florets, scale like with hairless projections and held close to the base of the bisexual lemma. Become hard, pale and shiny on maturity.

Of bisexual floret, egg shaped to oval, 2.5-3.5 mm long. Hairless or with a few short hairs near the tip. Becomes hard, pale and shiny on maturity.

Stamens -

Anthers - Abortive anther may occur in the sterile spikelets.

The group of 7 or 6 spikelets falls together at maturity.


Tear drop shape, shiny, pale brown, hairless, light lengthwise nerves, pointed tip.


Enclosed in fruit.



Key Characters:

Spikelets of 2 kinds; 1 fertile surrounded by 6 sterile, the group falling entire.


Life cycle:

Annual. Seed germinates in autumn and winter and grows in winter and spring producing a tuft of stems that flower from October to February.



By seed.

Flowering times:

Spring in western NSW.

November to February in SA.

October and November in Perth.

Spring in WA.

Seed Biology and Germination:

Vegetative Propagules:




Population Dynamics and Dispersal:

Spread by seed.

May occur in dense stands in wet years.

Origin and History:

Mediterranean and western Europe.





Temperate. Mediterranean.


Usually on sandy soils but also on clay soils in low lying areas, watercourses, gilgais, table drains and the edges of lakes.

Plant Associations:

Often grows with Lesser Canary Grass (Phalaris minor).

Black Box, Bimble Box, Bladder Saltbush and open grasslands.



Fodder but not highly valued. Palatable when very young and produces a large quantity but becomes unpalatable and rank at maturity.


Weed of crops, rotation crops, pastures, drains, roadsides and disturbed areas.


Not recorded as toxic.



Management and Control:

Graze heavily when young.


Eradication strategies:

Apply glyphosate in winter, and repeat in late spring if necessary, each year for several years. In crops and other situations a number of more selective herbicides can be used.

Herbicide resistance:

Biological Control:

Related plants:

Blue Canary grass (Phalaris coerulescens)

Canary grass (Phalaris canariensis) is similar but tends to have a more oval shaped seed head rather than an oblong one.

Lesser Canary grass (Phalaris minor) is very similar but the seed head is held well above the leaves and the spikelets fall singly rather than in groups.

Phalaris (Phalaris aquatica)

Reed Canary grass (Phalaris arundinacea)

Phalaris angusta

Phalaris arundinacea var. picta is and ornamental variety.

Plants of similar appearance:

Barley grass (Hordeum leporinum)

Cocksfoot (Dactylis glomerata)

Elephant Grass (Pennisetum purpureum)

Feathertop (Pennisetum villosum)

Hares Foot Grass (Lagurus ovatus) is similar but hairy.

Slender Foxtail (Alopecurus myosuroides)

Marsh Foxtail (Alopecurus geniculatus)

Meadow Foxtail (Alopecurus pratensis)

Timothy Grass (Phleum pratense)



Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P54. Photo.

Black, J.M. (1978). Flora of South Australia. (Government Printer, Adelaide, South Australia). P170. Diagram of spikelet.

Ciba Geigy (1981) Grass Weeds 2. CIBA GEIGY Ltd, Basle, Switzerland. P116. Diagrams.

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P131. Photo.

Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P66. Photo.

Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #960.6.

Marchant, N.G., Wheeler, J.R., Rye, B.L., Bennett, E.M., Lander, N.S. and Macfarlane, T.D. (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P979.

Wilding, J.L. et al. (1987). Crop weeds. (Inkata Press, Melbourne). P32. Diagrams. Photos.


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