[1] As a young man he assisted botanist Auguste de Saint-Hilaire (1779–1853) with studies of Brazilian flora.

[3] Around this time he also developed an interest in lichens, and in 1852 Tulasne published an anatomical and morphological study of this group.

It was in this work he introduced the term pycnidium to describe the asexual fruiting body found in many species of fungi.

He is credited with providing classification taxa for the following genera: Crucibulum, Glomus, Sebacina, Terfezia, Tilletia and Hypomyces (the latter genus with Elias Magnus Fries).

Some of his best work was done in collaboration with his brother, Charles Tulasne (1816–1884), such as "Fungi hypogaei" (1851) and the three-volume "Selecta fungorum carpologia" (1861–65).