Pilularia globulifera, commonly known as pillwort, is a type of aquatic fern that can be found in wet habitats such as marshes and wetlands. This small fern is also known by several other names including bladder fern, peppergrass, and globular pillwort. Its unique appearance, with small spherical sporangia that resemble small beads or pills, inspired the use of the name pillwort. Other synonyms for Pilularia globulifera include Pilularia punctata, Pilularia americana, and Mosigia globulifera. Despite its diminutive size, Pilularia globulifera plays an important role in maintaining the health of aquatic ecosystems, providing food and shelter for a variety of species.