Carex retrorsa, commonly known as Knotsheath Sedge or Retrorse Sedge, is a perennial herbaceous plant native to wet meadows, marshes, and the edges of ponds and streams in southern Canada and the northern United States. It typically forms dense clumps reaching 2 to 3 feet in height. The narrow, grass-like leaves are accompanied by inconspicuous greenish-brown flowers that appear in late spring to early summer. While the flowers are not showy, they provide ecological benefits to native pollinators.

Knotsheath Sedge is valued for its ability to thrive in wet conditions and is often used in ecological restoration projects, erosion control, and as a component in rain gardens. It is also suitable for naturalized areas and wildlife gardens, where it provides habitat and food for birds and insects. Carex retrorsa prefers consistently moist to wet soils and can tolerate partial shade, although it will also grow in full sun. It is generally low-maintenance, but gardeners should be aware that it can spread and may need to be managed to prevent unwanted colonization.CC BY-SA 4.0