Sonali Ray Assistant Professor,
Department of Botany,
Surendranath College, 24/2,
Mahatma Gandhi Road,
Kolkata- 700009., West Bengal India
Nanda Dulal Paria Professor in Botany (retired),
Department of Botany,
University of Calcutta,
35 Ballygunge Circular Road,
Kolkata-700019, West Bengal India