Yellow Nut Grass / Yellow Nut Sedge

(Cyperus esculentus)

Yellow nut weed

Status of yellow nut grass in Tasmania

  • Yellow nut grass is a declared weed in Tasmania under the Tasmanian Weed Management Act 1999. The importation, sale and distribution of yellow nut grass are prohibited in Tasmania.
  • The legal responsibilities of landholders and other stakeholders in dealing with yellow nut grass are laid out in the yellow nut grass Statutory Weed Management Plan.

What does yellow nut grass look like?

  • Yellow nut grass is an erect perennial (long-lived) sedge growing to 70 cm high. The stems are smooth, unjointed and triangular in cross section. The leaves are glossy light green, V-shaped in cross section, with small serrations on the margin and with a prominent mid-vein. The flowers are a cluster of yellowish brown spikelets which are carried on 3 to 9 flower stems. The seeds are yellow-brown and three angled. The root is an extensive system of rhizomes (underground stems), tubers (also called nuts) which occur singly at the ends of rhizomes, and basal bulbs (swellings of the stem base just below the soil surface).
  • Growth of new plants from tubers occurs in spring as temperatures rise. Flower stems form in late spring and flowers are produced in summer. All above-ground growth dies back in autumn.
  • Yellow nut grass spreads mainly via tubers, while seed viability is low. A single tuber can give rise to over 1900 plants and 7000 new tubers in one year! Tubers are not affected by frost or drying out. Tubers are spread by cultivation equipment and in contaminated soil, gravel or water.
  • Yellow nut grass is very similar to purple nut grass (C. rotundus) but can be distinguished by its brown to yellow flowers.
Yellow nut grass Yello nut grass Yellow nut grass
Image top, above left & middle: Yellow nut grass, © Louis M. Landry.
Image above right: Yellow nut grass tubers, © CDFA.

Impacts of yellow nut grass

  • Yellow nut grass is a serious weed of a wide range of crops.

Where does yellow nut grass occur?

  • Yellow nut grass is a pan-tropical to temperate species which has naturalised widely in tropical and temperate regions of the world. Yellow nut grass has naturalised widely in Australia although not as widely as purple nut grass, and is most significant on the north coast of Queensland.
  • Yellow nut grass has not managed to establish in Tasmania. 

What you need to do

  • If you locate yellow nut grass anywhere in Tasmania, or if you find a plant that you think could be yellow nut grass, immediately contact Biosecurity Tasmania on 03 6165 3777 to report this weed.

See also
Yellow Nut Grass Statutory Weed Management Plan
Weed Links and Resources

Other useful links
Pest Genie

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