Carex aquatilis aka Leafy Tussock Sedge

Carex aquatilis, or water sedge, belongs to the Cyperaceae family. It grows across northern Europe, Siberia, and much of North America. It is native to Britain and Ireland. In Britain, it grows beside lakes and streams in mountain districts. Elsewhere, it forms stands in northern marshes and high mountain wetlands. These wet places support much of its value for wildlife.

This upright, grass-like perennial spreads by rhizomes to form dense colonies. PFAF describes it as evergreen, with leaves present throughout the year. Its listed garden size is about 3.3 feet [1 metre] tall. Its spread can reach about 4.9 feet [1.5 metres]. A broader height range runs from 1–3.9 feet [0.3–1.2 metres]. Its spreading habit helps it fill wet ground. Allow room for colonies to grow when choosing a site.

The green flowers bloom in May and June in Chicago. PFAF gives July as the flowering month, so timing varies. Each plant bears separate male and female flowers. Wind carries the pollen between them. Seeds ripen during July and August, according to PFAF. Water and wind help move the seeds and perigynia. Wildlife can also carry them to new sites. The flowers add less colour than many garden perennials.

Grow water sedge in moist to wet soil. It suits full sun or partial shade. It accepts sandy soil, loam, and clay. It also tolerates mildly acid, neutral, and mildly alkaline conditions. Chicago Botanic Garden lists USDA hardiness zones 5–8. A bog garden gives it a suitable setting. Chicago also lists it for screens and hedges. PFAF describes cultivation and spring division as easy. Sow seed in moist soil in spring, with light shade. Small divisions benefit from time in pots before planting out.

Its rhizomes bind wetland soil and help limit erosion. Dense stands give birds nesting sites and shelter other wetland animals. Moose and waterfowl use it as forage. The tender stem bases can be eaten raw. They provide little food value and have a mild taste. PFAF reports no known toxins in these edible parts. Polluted water can still expose harvested plants to pathogens or parasites. PFAF lists no known medicinal uses. The supplied sources name no species-specific pests or diseases.