A semi aquatic weed Hydrocotyle verticillata Thunb. is reported from Nilgiri District for the first time along with its detailed description, phenology, photographs and relevant notes are provided here to facilitate easy identification of the taxa in the field.

Distribution, New addition, Apiaceae, Tamil Nadu, Nilgiri District

The findings presented in this research paper may serve as a valuable resource for researchers and students, especially within this region. The plant is commonly sold in local markets under the name Vallarai keerei, making accurate botanical identification essential.

K. Karunaidhasan, J. Shashikanth and P. Gopinath (2025). Hydrocotyle verticillata Thunb. (Apiaceae): A New Aquatic Weed from Nilgiri District and addition to the Flora of Tamil Nadu, India. Biological Forum, 17(10): 48-51.