Selaginella is the only genus in the Selaginellaceae family. Selaginellaceae are pteridophytes, and belongs to a class close to ferns. Selaginella includes more than 700 species, most of them native to tropical regions. Three species are present in the french flora. This genus is characterized by its dimorhic fronds, its two types of sporangia. Megasporangia are located at the « fronds » base, and contain only 4 big megaspores. Microsporangia are located at the « fronds » apex, and contain numerous microscopic spores, or microspores. This peculiarity is known as heterospory.