Cyperus eragrostis, commonly known as tall flatsedge, is a herbaceous perennial plant native to wetlands, marshes, and along the banks of water bodies in the West Coast and parts of Southeastern United States, Jamaica, and South America. It has a clumping growth habit with tall, erect stems that can reach up to 35 inches in height. The plant produces greenish-brown flower clusters at the tops of the stems during late summer to fall, which are not particularly showy but have a unique architectural quality.

Tall flatsedge is valued for its ability to stabilize soil and for its use in water gardens or naturalized areas where it can spread freely. It thrives in full sun to part shade and prefers consistently moist to wet soils, making it suitable for riparian plantings. While it can be an attractive and functional plant in the right setting, it is important to be aware of its invasive potential outside its native range. It can outcompete native vegetation and alter wetland ecosystems. Therefore, it is recommended to plant with caution and ensure it does not escape into natural areas.CC BY-SA 4.0