CHENNAI: The pollen of Parthenium, also known as ‘Congress Grass’, is an irritant, according to health experts. “The pollen causes allergies including respiratory. When it comes into contact with the skin, it may cause severe itching,” said Thirunarayanan T, Siddha physician and secretary of Centre For Traditional Medicine & Research in Adambakkam.
While it may not be too similar to coriander leaves in its morphological sense, it is often mixed with the coriander crops, albeit, in most cases, unintentionally, said Thirunarayanan. In these cases, ingesting the weed when it is used as a garnishing herb, mixed with coriander leaves, may not cause much damage. “When it is ground to make a chutney or juice, large quantities of weed may be consumed. This may lead to food poisoning.”
Ecologist Sultan Ismail recalled, “In the late 1980s, one of my colleagues who taught in a college in Calicut would come to Mysore, where I used to work during that period. She would take the route from Kerala to Mysore via Ooty.”
“She would tell me that when she reached a specific region in Karnataka, she would suddenly begin to start sneezing and it would persist during the entire period of her stay. Doctors diagnosed it as being caused by Parthenium,” he added.
In Karnataka, several cases of even suicides are said to have been reported a few decades ago, due to chronic respiratory problems caused by the weed. While it may not be as harmful for humans, the same cannot be said of cattle. Research indicates that substantial consumption of the weed (10 to 50 per cent) may result even in the death of cattle. However, in Tamil Nadu, skin irritation, rashes, hayfever and reduced milk quality among livestock, are more common, said a TANUVAS scientist.
Combating this invasive weed may be a difficult task, said D Narasimhan, retired associate professor of Department of Botany, Madras Christian College. “Unless we find a use for it, total eradication of the species is very difficult,” he said.