Puthanasurayil Nambiyath Balakrishnan served with the Botanical Survey of India (BSI) from 1958 until his retirement in 1993. He has contributed to many Indian floristic works and is an authority on the Eriocaulaceae and Euphorbiaceae families in India.

Balakrishnan received his MA in botany (1958) from the University of Madras and an MSc in plant taxonomy (1967) from the University of Liverpool, England. He gained his PhD in 1972 at Gauhati University, India, for his work on the Flora of Jowai (1981).

Since joining the Botanical Survey of India in 1958, Balakrishnan has worked in the offices at Coimbatore, Howrah, Shillong, Port Blair and Allahabad. He was involved in the establishment of the Andaman-Nicobar Circle of the Botanical Survey of India while based at Port Blair, where he oversaw the creation of the first air-conditioned herbarium in India. He worked in the Andaman and Nicobar Islands for 11 years.

At the time of his retirement Balakrishnan was Joint Director of the BSI, based at the Madras Herbarium, Coimbatore. Following his retirement, he continues to work as Emeritus Scientist at the BSI, in particular studying Euphorbiaceae taxonomy.

In total, Balakrishnan has amassed c.12,000 numbers, with significant collections from central and peninsular India, Assam, Maghalaya, Bhutan and the Andaman and Nicobar Islands. He has published nearly 200 scientific articles and is author of six books. Among the publications to which he has contributed are floras of Tamil Nadu (1989) and Madhya Pradesh (1992). He was also an editor of the Flora of India volumes 1, 2 and 23.

In recognition of his work, Balakrishnan was awarded the EK Janaki Ammal National Award in Plant Taxonomy by the Ministry of Environment Forests, Govt. of India, in 2006. He served as President of Indian Association for Angiosperm Taxonomy in 2003.

Sources:
Academia.edu:
http://independent.academia.edu/NambiyathBalakrishnan, accessed 1 June 2012 Some material also to be found in PBL.