Prof. Sahni was born on 14 November 1891, at Bhera, Shahpur, Punjab (Pakistan) ; received early education at Government College University, Lahore (where his father Ruchi Ram Sahni worked) and Punjab University, Lahore (Punjab) (1911). He learnt Botany under great Botanist Prof. S.R. Kashyap. He graduated from Emmanuel College, Cambridge in 1914 and did his doctorate work (D.Sc.) from University of London (1919) and another D.Sc. (1929) from University of Cambridge, UK. Briefly, he worked on Munich, Germany and returned to India in 1919 and was Professor of Botany, Banaras Hindu University, Varanasi and Punjab University, Lahore for about a year. In 1921 he was appointed as First Professor and Head, Department of Botany, University of Lucknow and served till 1949.
He founded the Palaeobotanical Society and established the Institute of Palaeobotany on 10 September, 1946 which initially functioned from the Botany Department of Lucknow University. On 3 April, 1949, Pt. Jawaharlal Nehru, Prime Minister of India laid the foundation stone of the new building of the Institute. A week later, on 10 April, 1949 Prof. Sahni succumbed to a heart attack. Now the Institute is named as Birbal Sahni Institute of Palaeobotany. He was member of Editorial Board of Chron Bot.
Prof. Sahni was deeply interested in Botany, Paleobotany and Geology. He made extensive contributions to the structure and affinities of certain zygopterid ferns. His studies on Indian Gondwana Plants, describe a number of entirely new fossil plants and involve revising several old species and their geological ranges. He also investigated the structure and affinities of various Indian Fossil Plants from Palaeozoic to the Quaternary beds.
He was a Fellow, of the Royal Society, London and Asiatic Society; Foundation Fellow, Indian National Science Academy (Vice President, 1935-36), Indian Academy of Sciences, and National Academy of Sciences (India) (President, 1943-44); Honorary Foreign Member, American Academy of Arts and Sciences. He was President, Botany Section (1921, 1938), Geology section (1926) of Indian Science Congress and Vice-President, Palaeobotany Section (1935) International Botanic Congress and General President (1940), Indian Science Congress.
Prof. Sahni received numerous awards, notable are: Barclay Medal by Asiatic Society (1936); Sir Cattamanchi Ramlinga Reddy National Prize; and Nelson-Write Medal of Numismatic Society (1944).
Prof. Sahni died on April, 1949.
