Volume three was given by Warming to Karl Erik Torsten Lagerberg (1882–1964), Swedish botanist and forestry professor. He taught at the Royal Forestry School (1918–1947) and studied forest tree diseases and fungi. He co-published Skogens skadesvampar and edited Svensk Botanisk Tidskrift from 1918. Lagerberg was elected to two national academies.

Johannes Eugenius Warming (1841–1924), commonly known as Eugen Warming, was a pioneering Danish botanist widely recognized as one of the founding figures of modern ecology. He authored the first textbook on plant ecology in 1895, introduced the first university course in the subject, and helped define the scope and content of ecological science. In 1975, ecologist R. J. Goodland asserted: “If one individual can be singled out to be honoured as the founder of ecology, Warming should gain precedence” ("The Tropical Origin of Ecology: Eugen Warming's Jubilee"). Warming wrote a number of textbooks on botany, plant geography and ecology, which were translated to several languages and were immensely influential at their time and later. Most important were “Plantesamfund and Haandbog i den systematiske Botanik”.