Born in Edinburgh, in 1853, son of botanist, John Hutton Balfour (1808-1884), Sir Isaac Bayley Balfour was a late-19th-century improver and botanist. He was educated at Edinburgh Academy and Edinburgh University. In 1874 he went to Rodriguez, Mexico, to study its botany and geology, on an expedition sponsored by the Royal Society. In 1879 he was appointed Professor of Botany at Glasgow University. That same year he went on a botanical and geological expedition to Socotra, in the Indian Ocean. Balfour was later appointed Sherardian Professor of Botany at Oxford and given charge of the Botanic Garden, Oxford which he opened to the public on Sundays. In 1887 he returned to Scotland where he began to improve and enlarge the Royal Botanic Garden, Edinburgh, particularly its plant collection and woodland, and became its Regius Keeper. In 1909 he went on a botanical expedition to Japan. In 1910 he went to China. He was knighted in 1920 and died on 30 November 1922.