Tussock Cottongrass

 

Tussock Cottongrass (Eriophorum vaginatum). Namakagon Fen State Natural Area, Bayfield County, Wisconsin.

Who knew the Lorax’s Truffula trees exist in real life? These cloud-like seedheads belong to Tussock Cottongrass (Eriophorum vaginatum), floating on the sag-and-swell of a peatmoss mat.

While peatmoss is squishy and unstable, cottongrass forms tough, knotted “tussocks” of roots and shoots that anchor each plant. Most of these sag-and-swell mats are floating islands above almost one hundred feet of water and loose mud. While untethered, the islands are solid and support lots of plant and animal life. The soft, antiseptic moss provides a nursery where plants from cranberries to tamarack trees can thrive.

Each cottongrass tussock is perennial and widens a basal cluster of leaves each year. Due to the deep, unstable nature of bogs, incapable of supporting the weight of logging equipment, many bogs and fens have been relatively undisturbed by industrial-level development. Many are still home to old-growth cottongrass tussocks. For decades, each tussock will grow bigger and bigger. Like trees, a good year will allow the tussock to expand exponentially and send out thousands of seeds. A bad year might severely stunt the cottongrass's growth.

Tussock Cottongrass (Eriophorum vaginatum). Namakagon Fen State Natural Area, Bayfield County, Wisconsin.

Old-growth graminoids also develop long, reaching roots extending several feet into a mass of dead and dying peatmoss. Along with the peatmoss itself, they’re incredible carbon sinks. Some of the carbon is recycled into breathable oxygen, while the rest is placed into underground stores of organic material. These bogs continue to absorb carbon as long as there are healthy communities with these specialized root systems. E. vaginatum is a very important member of the bog plant community in these boreal wetlands.

Not only do the tussocks sequester carbon and provide aesthetic value, they provide habitat inside the tussocks and root systems for amphibians, small mammals, invertebrates, and fungi. Birds and rodents feed on the seeds, or use the attached "cotton" as nesting material. Some butterflies even feed on the slender, wiry blades of tussock cottongrass.