Weed Identification

Australia > > Serrated Tussock

Serrated Tussock

Nassella trichotoma


Family: Poaceae.

Form: Grass

Origin: Native to Argentina, Uruguay, Chile, Peru, Bolivia, Paraguay and Brazil

Flowers/Seedhead: Seedhead: Young seedheads held among the leaves; mature seedhead to 25 cm long; glumes to 1 cm long; hard point at base of lemma bearded. Flowers spring and early summer.

Description: Perennial grass forming dense tussocks to 0.6 m high. Leaf blades to 0.5 mm wide, tightly rolled and with small serrations that can be felt when fingers are moved downward along the blade.

Distinguishing features: Distinguished by softly hairy nodes but usually concealed by leaf sheaths; ligule membranous and hairless, about 1 mm long; glumes purplish in the lower half; lemma to 3 mm long, without a cylindrical crown at the top; awn straight or obscurely twice bent, 23.5 cm long, attached off-centre to seed and remaining attached at maturity; open seedheads drooping over tussocks then detaching as a whole at maturity.

Dispersal: Spread by seed, mainly while in seedheads which break off at base and are carried by wind. Seeds are also moved by water, animals and in contaminated feed.

Open seedhead with purplish glumes, Goulburn, NSW, Oct
Inset: Tussock

Notes: Unpalatable to stock, and a major pastoral weed. Not limited by soil type or fertility. Appears to be limited to areas where the average temperature in the warmest month is less than 30C. The earliest naturalised vouchered specimen was collected near Yass in 1936. This species is also a weed in its native range and in South Africa, New Zealand and the USA.


    Noxious Weeds of Australia. W. Parsons and E. Cuthbertson, 1992, pages 111115. Biology of Australian Weeds. R. Groves et al. Vol. 1, 1995, pages 189202.

Distinctive drooping tussocks
Bacchus Marsh, December
photo J.R. Hosking

Left: seed
Right: On hillside, Goulburn, NSW
illustration: E. Mayfield

This weed has been included in the WEEDeck field guide as card G14

More information about WEEDeck is available from Sainty & Associates Pty. Ltd.


Australia > > Serrated Tussock


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