Horsetail Guide

Equisetum (pronounced /ˌɛkwɨˈsiːtəm/)[1] is the only living genus in the Equisetaceae, a family of vascular plants that reproduce by spores rather than seeds. They are commonly known as horsetails.

Equisetum is a "living fossil," as it is the only known genus of the entire class Equisetopsida, which for over one hundred million years was very diverse and dominated the understory of late Paleozoic forests. Some Equisetopsida were large trees reaching to 30 meters tall;[2] the genus Calamites of family Calamitaceae for example is abundant in coal deposits from the Carboniferous period.

A superficially similar but entirely unrelated flowering plant genus, mare's tail (Hippuris), is occasionally misidentified and misnamed as "horsetail"....