pillwort

Pillwort refers to a water fern belonging to the genus Pilularia. It is characterized by its small, round spore cases, known as sporocarps. The term "pillwort" specifically denotes a European plant, Pilularia globulifera, which is found near water bodies or in damp, acidic soil. The genus Pilularia itself is part of the Marsileaceae family and includes small, aquatic plants with thread-like fronds.12

It is important to distinguish pillwort from quillwort, which is a different type of seedless vascular plant in the order Isoetales, typically placed in the genus Isoetes. Quillworts are usually aquatic or semi-aquatic, with grassy, spikelike leaves growing from a corm-like base. Some quillwort species are listed as endangered due to habitat loss and pollution.3