Weed Identification

Australia > > Bathurst Burr

Bathurst Burr

Xanthium spinosum

Family: Asteraceae.

Form: Herb

Origin: Native of South America.

Flowers/Seedhead: Unisexual, male flowers in terminal spikes, female flowers in leaf axils. Flowers all year, mostly summer and autumn.

Description: Annual herb to 1 m high. Stems downy, spines 0.7–2.5 cm long. Leaves with prominent veins in middle of each lobe. Straw-coloured burrs each contain two brown or black seeds.

Distinguishing features: Distinguished by 3-pronged spines at base of leaves and at stem nodes; leaves 3–8 cm long, dark green above, greyish downy below, entire to divided into 3–5 linear segments; burrs 8–15 mm long and covered with hooked spines.

Dispersal: Spread by seed in burrs. Burrs are spread attached to animals, clothing and bags. Burrs float and are moved by water.


Leaves with prominent midvein,
spines 3-pronged

Notes: A major problem in pasture, crops and wasteland. Impedes shearing and is a major cause of vegetable fault in wool. Seedlings are poisonous to livestock, particularly horses and pigs. Can cause contact dermatitis in some humans. A number of insects and pathogens damage Bathurst Burr and biological control agents are being sourced from South America.

References:

    Noxious Weeds of Australia. W. Parsons and E. Cuthbertson, 1992, pages 318–321. The Biology of Australian Weeds. R. Groves et al., (eds), Vol. 1, 1995, pages 241–302.

Web References: Search Australian web sites for further information on this weed.

Seedling
photo J.J.Dellow & R.W.Medd
Burrs with hooked spines
Infestation, Balranald, NSW, January

This weed has been included in the WEEDeck field guide as card H25

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

 

Australia > > Bathurst Burr

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