Equisetum, commonly known as horsetail, is a genus of vascular plants that belong to the family Equisetaceae. These plants are characterized by their jointed stems and whorled leaves, which give them a unique appearance. Equisetum species are often found in wet or marshy areas and can grow in various environments, including forests and grasslands. Horsetails are ancient plants, with a lineage dating back over 300 million years, making them one of the oldest surviving plant groups. They reproduce through spores rather than seeds, and their stems contain silica, which contributes to their rigidity. Equisetum has been used in traditional medicine and as a natural abrasive due to its tough texture.