Juncus interior, commonly known as Interior Rush, is a perennial herb native to wet meadows, marshes, and the edges of water bodies in the central inlands of North America. It typically forms dense clumps reaching 1 to 3 feet in height. Interior Rush has cylindrical, hollow, grass-like leaves that may appear flat when young, and its inflorescence consists of small, greenish to brownish flowers that bloom in the summer. The flowers are not particularly showy but are interesting upon close inspection. The fruits are pale brown capsules that are consumed by waterfowl, which aids in seed dispersal.

Interior Rush is valued for its ability to stabilize soil and its tolerance of wet conditions, making it suitable for rain gardens, wetland restoration projects, and as a naturalizing element in water features. It is also used in ornamental water gardens for its upright form and texture. This plant prefers full sun to part shade and thrives in moist to wet soils with poor to moderate drainage. While generally low maintenance, it can become invasive in ideal conditions, spreading by rhizomes to form large colonies. It is resistant to many pests and diseases but can be affected by rust in some conditions.CC BY-SA 4.0