Author: Jan Scholten
Arthur John Cronquist (March 19, 1919 – March 22, 1992) was an American biologist, botanist and a specialist on Compositae. He is considered one of the most influential botanists of the 20th century, largely due to his formulation of the Cronquist system as well as being the primary co-author to the Flora of the Pacific Northwest, still the most up to date flora for three northwest U.S. States to date. Two plant genera in the aster family have been named in his honor. These are Cronquistia, a possible synonym of Carphochaete, and Cronquistianthus, which is sometimes included as a group within Eupatorium. The former was applied by R.M. King and the latter by him and Harold E. Robinson.
While Cronquist was in his mid-thirties, he began to question the usefulness of Adolf Engler & Karl Prantl's taxonomic system, laid down in their work Die Natürlichen Pflanzenfamilien (The Natural Plant Families), which had been the dominant system since the late 19th century. Although Cronquist was originally involved mostly with the family Asteraceae rather than with general systems, he began publishing on the topic in 1957 after much discussion with his peers concerning the challenge of forming a new taxonomic system. His initial publication (Cronquist, 1957) dealt purely with dicotyledons. At the time he began his work on his general scheme of classification, several others were working with the same goal in mind, including the American Robert F. Thorne, the Dane Rolf Dahlgren, and Armen Takhtajan of the U.S.S.R.. Each of them would go on to produce their own taxonomic schemes, though Cronquist's would prove to be the most widely adopted. While working on the project in the 1960s, Cronquist came to be close friends with Armen Takhtajan and both men put all of their information at one another's disposal. To this end Cronquist decided to learn Russian in order to have access to the scientific literature that the Soviet Union had accumulated, which was largely unknown to the rest of the world. He made several trips to the U.S.S.R. to meet with Takhtajan and other Soviet botanists and translated many botanical works from Russian throughout his life.
Cronquist's first overview of classification was published in 1960, followed by his The Evolution and Classification of Flowering Plants in 1968 with a revised and expanded second edition being released in 1988. This work also was a survey of the practices of systematic botany. In 1981 he published his landmark work, An Integrated System of Classification of Flowering Plants. The work divided flowering plants into 2 classes with a number of subclasses and down to the family level, with each taxon being described and defined. The system would go on to be adopted by several major projects in floristics, including the Jepson Manual (1993), Flora of North America, Flora of China, Flora of Australia and of course Gleason and Cronquist's Manual of the Vascular Plants, which was published in 1991.
Professor Cronquist was also a passionate and dedicated teacher who mentored countless students. He was a role model for what it meant to be a plant biologist and taxonomist. Among those who knew him, his baritone voice among the herbarium stacks will continue to chill the soul and warm the heart.