Equisetum giganteum, commonly known as Southern Giant Horsetail, is an evergreen perennial herb native to wetlands, including marshes, riverbanks, and moist open areas in South America, Central America, the Caribbean, and Mexico. It is one of the largest horsetails, with hollow, jointed stems that can grow 2–5 meters (6.6–16.4 ft) tall. The stems are green with black bands, giving them a bamboo-like appearance. Southern Giant Horsetail reproduces both by spores and vegetatively by rhizomes, which contributes to its potential invasiveness.

This plant is valued for its architectural form and prehistoric appearance, making it a striking feature in water gardens, bog gardens, and large containers. It thrives in full sun to part shade and requires consistently moist or wet soil conditions. While it does not produce flowers, its stems are visually appealing throughout the year. In cultivation, it is important to control its spread as it can become aggressive, particularly in areas with ideal growing conditions. To prevent unwanted spread, it can be grown in containers or areas with barriers. Equisetum giganteum is also used in phytoremediation projects due to its ability to absorb heavy metals from contaminated soils and water.CC BY-SA 4.0