| Birth Date: | January 3, 1893 |
| Death Date: | April 1977 |
| Nationality: | American |
| Workplaces: | Baltimore Junior College, Goucher College |
| Patrons: | National Research Council, American Philosophical Society |
| Alma Mater: | Oberlin College, University of Chicago |
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| Known For: | floral anatomy |
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LaDema Mary Langdon (5 January 1893 – April 1977) was an American botanist known for her work on floral anatomy, taxonomy, embryology, and morphology of Juglandaceae, Fagaceae, Cycas, and Dioon spinulosum. She was a member of the American Association for the Advancement of Science and was a professor at Baltimore Junior College and Goucher College. She earned her bachelor's degree from Oberlin College and her graduate degrees from the University of Chicago.[1]
Langdon's research focused on the stem anatomy of Cycas and Dioon spinulosum as well as the anatomy and taxonomy of floral species such as the family of Juglandaceae and Fagaceae. While the cycas species was previously investigated, Langdon's research was the first to investigate its growth rings.[2] In a study, she also described the anatomy of the packing tissue of the genus Carya.[3] Her works were funded by grants from the National Research Council and the American Philosophical Society.