Hannah Thompson Croasdale (1905–1999), Rolf Leo Grönblad (1895–1962), and Arthur Moreland Scott (1888–1963) are a trio of experts on Desmidiales or Desmids, an order of single-cellular green algae. They collaborated on multiple stuides and publications, primarily via correspondence, some of which were completed and published by Croasdale after the death of Grönblad and Scott.

Croasdale was the only one of the three with direct education in botany, having obtained a PhD from University of Pennsylvania with a thesis on freshwater algae. Following this she began working at Dartmouth in 1935, where she began as a technical assistant. Across her career she faced misogyny and discrimination from what she described as a "man's college" with an "anti-feminist dean", which slowed her career progression; she would not become a member of faculty until 1950 and then a proffesor in 1963 when she was named an associate professor of Phycology. Nonetheless, she was an incredibly prolific researcher and published practically yearly throughout her career.

Grönblad and Scott both began as hobbyists, Grönblad a Finnish dentist by trade and Scott an American structural engineer, and both developed into leading experts on Desmids. The two began collaborating in the early 1940s and would regularly consult each other on taxonomy and identification of collected Desmid specimens. Their earliest influential publication together was "New and Interesting Desmids from the South-Eastern United States", published in 1957. In the early 1960s they began consulting Croasdale on their collections, and the three began working and publishing together. After Grönblad and Scott's deaths in 1962 and 1963 respectively, Croasdale continued working on unfinished manuscripts and projects they had started together, publishing 5 works with the two as posthumous authors from 1964 to 1971.