Weed Identification

Australia > > Caltrop

Caltrop

Tribulus terrestris

Alternative Name(s): Cat-head, Bindii.

Family: Zygophyllaceae

Form: Herb

Origin: Native at least of the Mediterranean, now cosmopolitan. One Australian species is probably included under this name.

Flowers/Seedhead: Solitary in the leaf axils, 5-petalled. Flowers summer and autumn in southern Australia.

Description: Prostrate annual with stems to 2 m long. Leaves with 48 pairs of oblong leaflets, each leaflet to 12 mm long, the upper surface dark green and often with hairy margins, the lower surface paler and hairy. Fruit 1120 mm wide (including spines), comprising a cluster of 5 segments each with 2 larger divergent spines above and 2 smaller downward projecting spines below. Each segment with 15 seeds.

Distinguishing features: Distinguished by petals 210 mm long; style shorter than to slightly longer than length of stigma and fruit with 2 larger and 2 smaller spines per fruit segment.

Dispersal: Spines of fruit segments ensure rapid dissemination of seeds.

Confused With: Other small-fruited spiny Tribulus species.


Stigma not obvious below style
Somerton, NSW, Feb

Notes: A troublesome weed of wasteland, pastoral land, cropping, vineyards and recreation areas. Sharp spines on dry fruit hamper stock handling, are a nuisance in recreation areas and fruit may contaminate drying grapes. Photosensitisation, staggers and nitrate poisoning are also caused by stock grazing Caltrop. Young sheep are especially sensitive. A native insect and mite damage plants and overseas biological control has been used to reduce problems associated with this species.

References:

    Noxious Weeds of Australia. W. Parsons and E. Cuthbertson, 1992, pages 640643.

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


Ephysteris moth larvae

Native form of plant
Townsville, Qld, Nov
photo J.R.Hosking

Taproot

Seedlings
Griffith, NSW, Oct

This weed has been included in the WEEDeck field guide as card H64

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

 

Australia > > Caltrop

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