What is glyceria?

(Glyceria maxima - Poa aquatica)

Glyceria Flower1

  • Glyceria is a troublesome weed of farm dams, creeks, ponds and rivers in Tasmania.

How to identify glyceria

  • Glyceria is a perennial (long-lived) aquatic grass.
  • The leaves of glyceria are shiny, hairless and mid-green in colour, and grow 30-60 cm above the water surface. The leaves end in an abrupt point and the edges are rough to touch as the finger is drawn from tip down to the base.
  • Glyceria produces an extensive root system to a depth of approximately one metre. It also forms a sprawling mat of rhizomes (underground stems) which produce vast numbers of shoots which can quickly expand the size of the plant.
  • Glyceria produces a branched inflorescence (or spike of flowers) in spring and summer, comprising a large number of spikelets that range from yellow to green in colour, with a purplish tinge.
  • Glyceria stops growth at the onset of winter. Growth recommences in spring with a flush of new shoots from the rhizomes.
  • For help in identifying glyceria, search the Dennis Morris Weeds and Endemic Flora Database for glyceria illustrations. If you are still in doubt about the weed you are dealing with, contact your Regional Weed Management Officer on 1300 368 550 for help.
Glyceria Flower Glyceria - Dam
Image top: Glyceria in flower (K Fenner)
Image above left: Glyceria in flower (K Fenner)
Image above right: Glyceria in dam (K Fenner)

Glyceria in Tasmania

  • Glyceria is not declared in Tasmania.
  • Glyceria is found throughout Tasmania.
  • Glyceria occurs in rivers, creeks, dams, drains and other waterways with depths of up to two metres. In deeper waterways it sometimes forms vast floating mats which remain attached to the bank.
  • Glyceria infestations have also established on a number of roadsides in the absence of permanent standing water.
  • Dense stands of glyceria can reduce the holding capacity and access areas of dams and waterways.
  • In rivers, creeks, and irrigation and drainage channels, glyceria can restrict and even block water flow. Destruction of the weed can also result in a large amount of decaying vegetation polluting the water and blocking pump intakes, channels and ditches.
  • Glyceria accumulates toxic levels of hydrocyanic acid which has resulted in cattle deaths from cyanide poisoning.

Detailed management and control guidelines for glyceria can be found in the Glyceria Control Guide. Refer also to Herbicides for Glyceria Control. For further information see DPIPWE's Weed Links and Resources.

See also
Glyceria Control Guide
Herbicides for Glyceria Control
Weed Links and Resources

Other useful links

Pest Genie

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