Philippe Édouard Léon Van Tieghem (April 19, 1839 - April 28, 1914) was a French botanist who was a native of Baillleul in the département of Nord.
After obtaining his baccalauréat in 1856, he studied at the École Normale Supérieure, and after receiving agrégation he worked in the laboratory of Louis Pasteur (1822–1895). Here he performed research involving the cultivation of mushrooms. He is credited with creation of the eponymous "Van Tieghem cell", a device mounted on a microscope slide that he used to observe the development of a fungus' mycelium.
In 1864 he earned his doctorate in physical sciences with a thesis titled Recherches sur la fermentation de l'urée et de l'acide hippurique, and two years later obtained a doctorate in natural history. From 1873 to 1886 he taught classes at the École centrale des arts et manufactures, and from 1878 to 1914 was a professor at the Muséum national d'histoire naturelle. During this time (1899–1914) he was also an instructor at the Institut agronomique in Paris.
In 1871 he became a member of the Société philomathique de Paris, and in 1876 gained membership to the Académie des sciences. In 1873 he translated botanical writings of Julius von Sachs from German into French as Traité de botanique conforme à l'état présent de la science. Other noted publications by Van Tieghem are as follows:
In 1876 he was the first to describe blastomycosis, a fungal infection that is also known as "Gilchrist disease", named after Thomas Casper Gilchrist (1862–1927), who published a treatise on the condition in 1896.