John Leonard Riddell, (1807-1865), American chemistry professor, botanist, writer, and medical doctor. He was born in Massachusetts, but most of his botanical observations were in the central states from Ohio southward. His important work was a “Synopsis of the Flora of the Western States” defined at the time as the territory from the Allegheny mountains to the Platte River in Missouri Territory. It was in great part a compilation. He later published Catalogus Florae Ludovicianae.

He served as Adjunct Professor of Chemistry and Lecturer on Botany in the Cincinnati Medical College where he also received his M.D. and he later became chair of the Chemistry Dept. in the Medical College of Louisiana (which then became the University of Louisiana), which position he held until his death. It was there he invented the binocular microscope. The plant genus Riddellia was named for him. His descriptions for some species of asters were updated by Guy L. Nesom (b. 1945), American botanist who has published papers on the nomenclature of asters.