Scientist, In-Charge, Botanical Survey of India, Southern Regional Centre, T.A.N.U. Campus, Lawley Road, Coimbatore 641 003, Tamil Nadu to authenticate your plant specimen and you can also deposit the same in that herbarium. See the attached file.
As suggested by Subir sir, you may contact the BSI Coimbatore centre for authentication of samples. Now as per government norms, the payment mode has been modified and it should be through online payment only and not in Demand Draft form. For more details you please contact the office number (0422 2432788)