Equisetaceae

Perennial fern allies with coarse upright hollow jointed stems with alternating vertical ridges and grooves, and also elongate underground stems (rhizomes; well-known to gardeners); includes Horsetails and Scouring Rushes. Produce spores, not seeds, in a cone (sporangiophore) at the tip of the stem. Leaves are scale-like, in whorls, and fused to form a sheath with teeth at each joint (node) in the stem. Branches, if present, are also jointed, hollow and often whorled. Most species are terrestrial, a few aquatic.

The only living genus in the ancient Horsetail family, its fossil relatives occurring at least 300 million years ago.