Jean Baptiste Saint-Lager, born in 1825 in Lyon and died in 1912, was a French botanist and physician.

[2] In 1850 he worked as a doctor of medicine at the University of Paris, where he remained in this profession for twelve years.

[2] In 1862, he began travelling to make collections for his research on both botanical and medical topics, during which time he devoted himself to scientific studies.

Although Chatin's findings were disputed by scholars representing the biological conservatism of the times, Jean Baptiste Saint-Lager supported Chatin's views and wrote a careful review of 43 different pathogenetic theories of goitre.

[3] In Saint-Lager's study of herbaria, he dealt primarily with the process of nomenclature (phytonymy) and of plant taxonomy.