Juncus dubius, commonly known as wrinkled rush, is a perennial herb native to the wetlands of California, including the Coast Ranges, Transverse Ranges, and the southern Sierra Nevada, and into Baja California. It is typically found in marshes, wet meadows, and along riverbanks, where it forms dense tufts from a horizontal rhizome. This rush can reach a height of up to 28 inches (71 cm) and is characterized by its erect, cylindrical green stems that have a distinctive wrinkled texture. The inflorescence is an open array of branches bearing small clusters of flowers, each with reddish or brownish-green tepals and bristles at the tips. The fruit is a capsule that turns red or brown as it matures.

Wrinkled rush is valued for its ability to stabilize soil and filter water in wetland restoration projects. It is also used in ornamental water gardens and naturalized plantings. In cultivation, Juncus dubius requires consistently moist or wet soil and can grow in full sun to part shade. It is relatively low maintenance, but gardeners should ensure it does not dry out. While not commonly afflicted by diseases, it can be susceptible to rust. Wrinkled rush is not known for aggressive roots or significant pest problems. It is not typically invasive when grown within its native range but should be monitored in other wetland environments to prevent unwanted spread.CC BY-SA 4.0