Horsetails are ancient plants belonging to the genus Equisetum. They are characterized by their jointed stems and whorled leaves, which give them a unique appearance. Horsetails thrive in wet environments, such as marshes and along riverbanks, and can grow up to three feet tall. They reproduce using spores rather than seeds, which are produced in cone-like structures at the tips of their stems. These plants have a long history, dating back over 300 million years, making them one of the oldest living plant species. Horsetails are often considered a weed due to their aggressive growth and ability to spread quickly. They are also known for their high silica content, which has led to their use in traditional medicine and as a natural abrasive.