Karl Adolph Hansen was a German

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 botanist. He graduated in 1887 at the University of Würzburg

University of Würzburg

The University of Würzburg is a university in Würzburg, Germany, founded in 1402. The university is a member of the distinguished Coimbra Group.-Name:...

 on a thesis entitled "Geschichte der Assimilation und Chlorophyllfunktion" (supervised by Julius Sachs). He was professor of botany

Botany

Botany, plant science, or plant biology is a branch of biology that involves the scientific study of plant life. Traditionally, botany also included the study of fungi, algae and viruses...

 at the Justus Liebig-Universität Gießen

University of Giessen

The University of Giessen is officially called the Justus Liebig University Giessen after its most famous faculty member, Justus von Liebig, the founder of modern agricultural chemistry and inventor of artificial fertiliser.-History:The University of Gießen is among the oldest institutions of...

 1891-1920. He had very broad academic interests, including history and archaeology. However, he always worked alone, supervised very few doctoral students (4 in 39 years), and stood outside the development of experimental physiological botany among his contemporaries.
Hansen wrote scholarly works on Goethe's

Johann Wolfgang von Goethe

Johann Wolfgang von Goethe was a German writer, pictorial artist, biologist, theoretical physicist, and polymath. He is considered the supreme genius of modern German literature. His works span the fields of poetry, drama, prose, philosophy, and science. His Faust has been called the greatest long...

 Metamorphosis of Plants

Metamorphosis of Plants

Johann Wolfgang von Goethe, the great German poet and philosopher published in 1790 the seminal essay Versuch die Metamorphose der Pflanzen zu erklären, known in English as Metamorphosis of Plants. In this work, Goethe essentially discovered the homologous nature of leaf organs in plants, from...

and had a fierce dipute over this hypothesis with Houston Stewart Chamberlain

Houston Stewart Chamberlain

Houston Stewart Chamberlain was a British-born German author of books on political philosophy, natural science and the German composer Richard Wagner. He later became a German citizen. Chamberlain married Wagner's daughter, Eva, some years after Wagner's death...

.

The wind controversy with Eugenius Warming

In 1901, Hansen wrote a treatise of the dune

Dune

In physical geography, a dune is a hill of sand built by wind. Dunes occur in different forms and sizes, formed by interaction with the wind. Most kinds of dunes are longer on the windward side where the sand is pushed up the dune and have a shorter "slip face" in the lee of the wind...

 vegetation of the East Frisian Islands

East Frisia

East Frisia or Eastern Friesland is a coastal region in the northwest of the German federal state of Lower Saxony....

, in which he proposed salt

Sodium chloride

Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...

 as the main plant-distributing factor. He thereby neglected previous work by Warming

Eugenius Warming

Johannes Eugenius Bülow Warming , known as Eugen Warming, was a Danish botanist and a main founding figure of the scientific discipline of ecology...

 and Raunkiær

Christen C. Raunkiær

Christen Christensen Raunkiær was a Danish botanist, who was a pioneer of plant ecology. He is mainly remembered for his scheme of plant strategies to survive an unfavourable season and his demonstration that the relative abundance of strategies in floras largely corresponded to the Earth's...

 contending the importance of the wind. Eugenius Warming

Eugenius Warming

Johannes Eugenius Bülow Warming , known as Eugen Warming, was a Danish botanist and a main founding figure of the scientific discipline of ecology...

 strongly criticised Hansen's work and Hansen returned by criticising Warming's Lehrbuch der ökologischen Pflanzengeographie

Plantesamfund

Plantesamfund - Grundtræk af den økologiske Plantegeografi, published in Danish in 1895 by Eugen Warming, and in English in 1909 as Oecology of Plants: An Introduction to the Study of Plant Communities, by Warming and Martin Vahl, was the first book to be published having the word ecology in its...

, to which Warming gave another polemic reply.

Selected scientific works

• Hansen, Ad. (1882) Geschichte der Assimilation und Chlorophyllfunction. Leipzig: Wilhelm Engelmann, 90 pp.
• Hansen, Ad. (1885) Die Ernährung der Pflanzen. Leipzig und Prag, Freytag & Tempsky, 1885. 268 pp. (Das Wissen der Gegenwart, vol. 38.)
• Hansen, Ad. (1907) Goethes Metamorphose der Pflanzen. Geschichte einer botanischen Hypothese. 2 Teile. Gießen: Alfred Töpelmann
• Die Pflanze : mit 33 Abb.. Göschen, Berlin 1914 digital
• Hansen, Ad. (1919) Goethes Morphologie (Metamorphose der Planzen und Osteologie) Ein Beitrag zum sachlichen und philosophischen Verständnis und zur Kritik der morphologischen Begriffsbildung. Giessen: Alfred Töpelmann, 1919. 200 pp.