Cyperus rotundus, commonly known as nut grass or purple nutsedge, is a perennial sedge native to Africa, southern Europe, and southern Asia, often found in wetlands, along riverbanks, and in agricultural fields as a common weed. It typically grows up to 55 inches tall with leaves sprouting from the base in ranks of three, which are glossy and can be mistaken for grass from a distance. The flower stems have a triangular cross-section and bear small, umbrella-like clusters of bisexual flowers that are not particularly showy. The plant is known for its tubers, which resemble nuts and are a survival mechanism, allowing it to thrive in dry conditions.

Cyperus rotundus is valued for its aromatic and medicinal properties, used in traditional medicine to treat various ailments. It is also a staple carbohydrate in some tropical regions. In cultivation, it prefers full sun to part shade and can tolerate a range of soil types, though it thrives in moist, well-drained soils. Due to its aggressive growth and ability to form dense colonies through its tubers, it can be problematic in gardens and agricultural lands, often considered a noxious weed. It is frequently invasive outside of its native range, so caution is advised before planting.CC BY-SA 4.0