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Weeds: Erect tar vine
Erect tar vine is also known as erect spiderling (Boerhavia erecta)
Erect tar vine is a fast-growing perennial scrambler that invades annual crops such as maize, sorghum, peanuts, beans, and young orchards. It has been used as pig fodder in the Americas, but its pest status outweighs its benefits. In northern Australia it would cause crop losses, degrade the environment and provide harbor for feral animals.
Keep a Top Watch
Several native species of tar vine occur in Australia, but erect tar vine has not been found here yet. Native tar vines also invade disturbed and cultivated sites, but the taller, erect tar vine would be a more serious weed. There is a constant threat that it could enter Australia. Be vigilant for foreign vessels or planes carrying plant material and report any suspect weeds to Quarantine immediately.
Profile: Erect tar vine rapidly invades cultivated plots, pastures and the understorey of native woodlands. Its seeds can be spread long distances by accident, attached to clothing, fur, feathers, farm implements and vehicles.
Identification: Erect tar vine is a spreading broad-leaved herbaceous plant to 1m tall. It has a strong taproot and sticky, reddish stems. Dense infestations have a reddish haze above them caused by the erect flowering stems. Clusters of small white or pale pink flowers produce club-shaped, ribbed, sticky seeds.
Photos below: Erect tar vine is a fast-growing perennial scrambler. The flowers are small and white or pale pink. Dense infestations of the weed have a reddish haze.
Distribution: Native to the American tropics, erect tar vine is now a widespread weed, occurring in Africa, India, Thailand, Indonesia, New Guinea and Western Polynesia.
Threat: Erect tar vine could enter Australia as a contaminant of clothing and footwear, or on migratory birds. Infestations would reduce crop yields and horticultural production in northern Australia, and damage natural ecosystems. The annual cost of weeds in Australia is estimated to be $3.3 billion. New weeds add to the financial burden and must be prevented.
Quarantine: Throughout northern Australia, AQIS officers conduct regular weed surveys and help promote public awareness about new weed threats. Early detection and response minimises damage and costs.