Purple Nut Grass
Status of purple nut grass in Tasmania(Cyperus rotundus)
- Purple nut grass is a declared weed in Tasmania under the Tasmanian Weed Management Act 1999. The importation, sale and distribution of purple nut grass are prohibited in Tasmania.
- The legal responsibilities of landholders and other stakeholders in dealing with purple nut grass are laid out in the Purple Nut Grass Statutory Weed Management Plan.
What does purple nut grass look like?
nut grass is an erect perennial (long-lived) sedge growing to 50 cm
high. The stems are smooth, unjointed and triangular in cross section.
The leaves are glossy dark green, V-shaped in cross section, with small
serrations on the margin and with a prominent mid-vein. The flowers are a
cluster of reddish/purplish brown spikelets which are carried on 3 to 9
flower stems. The seeds are black, brown, olive or gray, ovoid-shaped
and beaked. The root is an extensive system of rhizomes (underground
stems), tubers (also called nuts) which are purplish in colour, and
basal bulbs (swellings of the stem base just below the soil surface).
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.
- Purple nut grass
spreads mainly via tubers, as seed viability is low. A single tuber can
give rise to over 600 plants, and a cubic metre of soil may contain over
50 000 tubers! Tubers can remain dormant in the soil until dormancy is
broken by the rhizome being cut into pieces. Tubers can be spread by
cultivation equipment and in contaminated soil, gravel or water.
- Purple nut grass is very similar to yellow nut grass (C. esculentus) but is distinguished by its brown to purple flowers.
Image top: purple nut grass (Image: Luigi Rignanese)
Images above: purple nut grass (Image: Luigi Rignanese)
Impacts of purple nut grass
- Purple nut grass is a serious weed of a wide range of crops, and dense infestations can reduce crop yields by over 75%.
Where does purple nut grass occur?
nut grass is a pan-tropical species of doubtful origin which has
naturalised widely in tropical and warm-temperate regions. In Australia,
purple nut grass has naturalised in all mainland States and
- Purple nut grass has not managed to establish in Tasmania.
What you need to do
- If you locate
purple nut grass anywhere in Tasmania, or if you find a plant that you
think could be purple nut grass, immediately contact your Regional Weed
Management Officer on 1300 368 550 to report this weed.
Purple Nut Grass Statutory Weed Management Plan
Weed Links and Resources
Other useful links
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