The plant, Vernonia anthelmintica, or Purple Fleabane, seems to be good for treating psoriasis.

Our findings certainly show that the traditional use is not just an old wives' tale Dr Amala Raman, King's College

Its seeds contain a chemical that stops inflammation, say scientists at Kings College, London.

Dr Amala Raman says they hope to develop a herbal product from the daisy.

It grows in tropical countries and is a traditional medicine in India.

"Normally, antipsoriatic compounds are either cytotoxic (eg. methotrexate) or anti-inflammatory (eg. steroids)," he said.

"What is exciting is that Vernonia has both activities. Our findings certainly show that the traditional use is not just an old wives' tale."

'Difficult condition'

Psoriasis causes the skin to become very inflamed, producing red, thickened areas with silvery scales, mainly on the scalp, elbows, knees and lower back.

Current treatments for the condition, which affects between 1% and 3% of the population in the US and Europe, are not completely effective and can have nasty side-effects.

Gladys Edwards of UK patient support charity, the Psoriasis Association, welcomed the research.

"Psoriasis is a difficult condition," she told BBC News Online. "It's long-term, it relapses and any new treatments that will help people manage the condition are welcome."

The research was funded by Phytopharm plc, a botanical pharmaceutical company set up to develop new medicines from plants.

It was revealed at the British Pharmaceutical Conference in Manchester.