The field horsetail or common horsetail, is a herbaceous perennial plant, native throughout the arctic and temperate regions of the northern hemisphere. The plant contains several substances which can be used medicinally. It is rich in the minerals silicon, potassium, and calcium. The buds are eaten as a vegetable in Japan and Korea in spring time. All other Equisetum species are toxic.
Fun Fact It has been suggested that the pattern of spacing of nodes in horsetails, wherein those toward the apex of the shoot are increasingly close together, inspired John Napier to discover logarithms.