Astrid Maria Cleve von Euler (22 January 1875 – 8 April 1968) was a Swedish botanist, geologist, chemist and researcher at Uppsala University.

[1][2][3] Her younger sisters were Agnes Cleve-Jonand (1876-1951), a visual artist and pioneer of Modernism in Sweden and Célie Brunius (1882-1980), a journalist.

[4] Her father taught her the basics of science in his laboratory, where he studied plankton; this formative experience sparked Cleve's interest in diatoms.

They raised five children,[6] three of whom were born shortly after she left the University,[7] one of them being the later physiologist and Nobel laureate Ulf von Euler.

[6] The marriage ended in 1912; seventeen years later, in 1929, Hans von Euler-Chelpin won the Nobel Prize in Chemistry for his studies of fermentation.

After her teaching job ended, she moved to Värmland, where she lived from 1917 to 1923 and was head of the Skoghallsverkens Forskningslaboratorium (forestry laboratory), a subsidiary of the Uddeholm Company; she continued to conduct research there.

[7] She obtained her doctoral degree in May 1898 at Uppsala University, 23 years old,[5] on a thesis entitled Studier ofver några svenska väksters groningstid och förstärkningstadium,[10] "Studies on the germinating time and the juvenile stage of some Swedish plants".

Her research there, undertaken between 1920 and 1925, comprised 23 papers on various topics, including the lignin produced during sulfite pulp manufacturing and how to determine the lignin content of a particular wood, the composition of pine and spruce needles, carbon dioxide's role in plants, methods for separating pulp by-products, petroleum, and coal.

[6] Her connection to teaching continued as, during this period, she also authored a popular science book on selenium as well as an introductory textbook in applied biochemistry.

[8] In her discourse with the contemporary Scandinavian scientific establishment, Cleve found conflict as a proponent of the oscillation theory.

The theory held that Fennoscandia's surface had oscillated up and down like a pendulum losing momentum after the Fennoscandian Ice Sheet melted.

Cleve argued that "Svea River" should be made a national monument but that it was not the outlet of the ancient Ancylus Lake as Munthe and von Post claimed.

[12] The controversy turned personal when as Munthe defended his geological interpretation in the newspapers she responded by accusing him of having unscientific reasons to advance his idea of what Svea River was.

Still in use today, Die Diatomeen von Schweden und Finnland covered approximately 1600 diatom species and their taxonomy, distribution, ecology, and fossils.

[8] After her 1945 return to Uppsala University, Cleve participated in the geology department and contributed theories about changes in the Baltic Sea's water level during the Quaternary period.