Carex holostoma, commonly known as Arctic Marsh Sedge, is a perennial herbaceous plant belonging to the sedge family, Cyperaceae. This species is a characteristic component of Arctic and subarctic ecosystems, playing a role in the ecological dynamics of its specialized habitats. Its significance lies in its adaptation to cold climates and its contribution to the biodiversity of tundra and wet meadow environments. The Arctic Marsh Sedge typically forms dense tussocks or clumps, growing to a height of approximately 15 to 40 centimeters. Its culms are erect, triangular in cross-section, and smooth. The leaves are basal, linear, and channelled, measuring about 2 to 4 millimeters in width, and are typically shorter than the culms. The inflorescence is a terminal spike, often subtended by a short bract. The spike is typically androgynous, meaning it contains both male and female flowers, with the male flowers usually located at the apex and the female flowers below. The perigynia, which enclose the achenes, are ovoid to obovoid, pale green to straw-colored, and possess a short, bifid beak. The achenes are lenticular and brown at maturity. The root system is fibrous, anchoring the plant firmly in its substrate. Native to circumboreal regions, Carex holostoma is found in Arctic and subarctic areas of North America, Europe, and Asia. Its natural habitat includes wet, open environments such as tundra, bogs, fens, wet meadows, and the shores of lakes and streams. It thrives in cool, moist conditions and is adapted to a short growing season. While not widely cultivated, its presence in its native range is indicative of its ecological niche. The ecological importance of Arctic Marsh Sedge is primarily as a producer in its native environment, contributing to the base of the food web. It provides habitat and forage for various Arctic fauna. Its ability to colonize and stabilize wet soils also plays a role in landscape processes. There is no established ornamental, agricultural, medicinal, or culinary use documented for Carex holostoma. A notable characteristic of Carex holostoma is its adaptation to cold, often waterlogged soils. The plant's morphology, including its tussock-forming habit and robust root system, helps it withstand harsh environmental conditions. Its reproductive strategy, typical of sedges, involves wind pollination and the dispersal of achenes, often facilitated by water. The specific adaptations of its perigynia and achenes are crucial for its survival and reproduction in the challenging Arctic climate.