Equisetum is a genus of vascular plants that reprouce by spores rather than seeds. The genus includes 15 species commonly known as horsetails and scouring rushes. It is the only living genus in class Equisetopsida, formerly of the division Equisetophyta (Arthrophyta in older works), though recent molecular analyses place the genus within the ferns (Pteridophyta). Other classes and orders of Equisetopsida are known from the fossil record, where they were important members of the world flora during the Carboniferous period.