Jean Louis Léon Guignard (13 April 1852 in Mont-sous-Vaudrey – 7 March 1928 in Paris) was a French pharmacist and botanist.
In 1887, he succeeded Gaspard Adolphe Chatin as chair of botany at the Ecole Supérieure de Pharmacie in Paris.
[1] Along with biologist from Kyiv Sergei Navashin, he is credited as the co-discoverer of double fertilization in flowering plants.
[3] In addition, he conducted significant research on the origin and structure of integuments for a large number of seeds.
[4] In 1892, botanists Pierre Viala and Louis Etienne Ravaz published Guignardia,which is a genus of fungi in the family Botryosphaeriaceae and named in Guignard's honour.