HYDERABAD: If you are planning to prepare dishes like vepudu, pappu or podi using the green leafy vegetable Ponnaganti kura, better avoid using the vegetable, as under the guise of Ponnaganti kura, many vegetable vendors in Hyderabad are selling alligator weed, an invasive alien plant species containing toxic concentrations of lead, cadmium, manganese, zinc and iron. Alligator weed is an invasive alien aquatic plant species native to South America that grows abundantly in polluted lakes in and around Hyderabad and as a result absorbs toxic elements from the polluted water which gets distributed across the plant’s root, stem and leaves.
It bears the scientific name of Alternanthera philoxeroides and its leaves closely resemble the Indian Ponnaganti kura which has scientific name of Alternanthera sessilis.
A study conducted by botanists from University of Hyderabad (UoH) for which they took samples of alligator weed being sold as Ponnaganti kura at different locations in the city, has reported concentration of Lead in the weed to be as high as 230 milligrams per kilogram(mg/kg). The maximum permissible limit(MPL) for lead in vegetables as per international organisations is 0.3mg/kg. Lead toxicity is associated with health problems like cardiovascular diseases, decreased kidney functioning and anaemia.
In some samples another toxic heavy metal, cadmium was found as high as 54mg/kg, much higher than MPL of 0.1mg/kg. Cadmium exposure can damage kidney, lungs and bones. Similarly, zinc concentration was found to be as high as 692mg/kg against MPL of 100mg/kg. Dr Sateesh Suthari of Department of Plant Sciences, UoH, lead author of the research paper, ‘Health risks of leafy vegetable Alternanthera philoxeroides (Alligator weed) rich in phytochemicals and minerals’, says, “Polluted water bodies in and around GHMC limits are infested with alligator weed, particularly at Hussainsagar, Sakhi cheruvu, Mir alam tank, Thallakunta, polluted water bodies in and around Hitech city like Raidurgam cheruvu, water bodies at Moosapet, Uppal, Nacharam, Prakash nagar, Cherlapally, Rampally and along the banks of Musi river. I did not come across farms growing alligator weed anywhere in and around GHMC limits..”
He further said, “As part of study, other districts too were visited. Even there we found alligator weed growing in polluted water bodies in abundance and it being sold by vegetable vendors but we did not come across any farm growing alligator weed.” Dr Suthari said, “It is very difficult for a layman to distinguish between Alligator weed and Ponnaganti koora. The main difference is that Ponnaganti kura leaves have deeper shade of green and have slender leaves.”