AT A GLANCE
- Common Name: Common Cottongrass
- Scientific Name: Eriophorum angustifolium
- Category: Plants
- Subcategory: Flowering Plants
- Range: Circumboreal across northern and temperate regions of the Northern Hemisphere, widespread in northern Europe, northern Asia, and North America from Alaska to the northern United States
- Habitat Type: Acidic wet peat bogs, blanket bogs, quaking mires, wet heathlands, acidic flushes, and peat pool margins with permanent waterlogging
- IUCN Red List Status: Least Concern
- Lifespan: Perennial rhizomatous sedge
- Diet: Autotrophic (photosynthetic)
- Average Size/Weight: Stem height 30 to 60 cm; cotton heads 2 to 3.5 cm long
- Key Defining Feature: Iconic northern peatland sedge producing multiple drooping, brilliant snow-white fluffy cotton-like seed plumes that dance in the wind across wild peat bogs
Overview
Common Cottongrass (Eriophorum angustifolium), also poetically known as Bog Cotton or Cotton Sedge, is one of the most evocative, beloved, and photogenic plants of the wild, waterlogged peatlands of the Northern Hemisphere. Not a true grass, but a member of the sedge family Cyperaceae, it transforms bleak, sodden moorlands and Arctic tundra into shimmering seas of snowy white every summer. Each slender stem is crowned with multiple drooping, silky pom-poms that flutter like miniature clouds in the highland breeze.
Biology and Physical Characteristics
Eriophorum angustifolium is a perennial sedge that spreads via extensive creeping underground rhizomes, forming dense, stabilizing turf in soft peat. Its flowering stems (culms) are erect, stiff, and smooth, reaching 30 to 60 cm in height, bearing narrow, channeled, dark green leaves with triangular tips that often turn bright crimson in autumn. In early spring, it produces small, inconspicuous brownish-green spikelets pollinated by the wind. By midsummer, the perianth segments of these flowers elongate into hundreds of long, hair-like bristles composed of pure cellulose, forming three to seven drooping, extraordinarily soft, cotton-like tassels of dazzling snow-white.
Behavior and Ecology
Common Cottongrass is a master engineer of the peat bog ecosystem. Its dense rhizome networks bind loose, saturated peat mud together, preventing erosion and creating stable hummocks upon which other bog plants and Sphagnum mosses can establish. Its hollow stems and root tissues contain expansive aerenchyma channels that transport oxygen down into waterlogged, oxygen-depleted peat mud. The fluffy white ‘cotton’ heads function as wind-dispersal parachutes: when summer breezes sweep across the bog, the silky plumes catch the air, carrying the tiny attached seeds miles across the landscape. Historically, rural communities gathered the silky plumes to stuff pillows and mattresses.
Conservation and Human Impact
Common Cottongrass is assessed as Least Concern on the IUCN Red List due to its immense circumpolar distribution across vast boreal and Arctic peatlands. It is one of the hardiest pioneer colonizers of drained or degraded peat cuttings, making it a cornerstone plant for commercial peatland restoration and carbon sequestration projects throughout Scotland, Ireland, and Scandinavia.
Interesting Factoid
The fluffy white ‘cotton’ on Common Cottongrass is not cotton at all, but hundreds of microscopic silk-like bristles made of pure cellulose that act like miniature parachutes, carrying seeds on the wind across miles of open moorland.