Axel Gudbrand Blytt (19 May 1843 – 18 July 1898) was a Norwegian botanist and geologist. His father was Matthias Numsen Blytt, also a botanist. Axel Blytt served at the Christiania Herbarium at the University of Oslo from 1865, first as a conservator, then, from 1880, as a professor. Based partly on his father's work, he published in the 1870s the book Essay on the Immigration of the Norwegian Flora during Alternating Rainy and Dry Periods. He is today best known for developing the Blytt-Sernander theory of climatic change. His work, Essay on the Immigration of Norwegian Flora. (1876) was read by, and influenced, Charles Darwin.