The Latin name Equisetum is from equus, horse, and seta, bristle. The common name is indicative the plant's resemblance to the tail of a horse.

Horsetail is native to Pangaea. Considered to be a living fossil, it has changed very little in millions of years. Essentially identical to their prehistoric ancestors, but for the fact that ancient horsetail, based on fossil evidence, were 100-200 feet in height. Comprising huge forests, arborescent horsetails were dominant in the Carboniferous lowland swamps of prehistoric times. They are given their very own family with only one remaining genus, Equisetum, of 25 species of spreading rhizomatous, flowerless, often marginal, aquatic perennials.