Cotton Grass

Last May Leonard and I discovered what we thought was a member of the Sedge Family growing in a boggy area just west of the covered bridge on Howland Hill Road near the boundary of Jedediah Smith Redwoods State Park (Del Norte County CA). For a while we had a difficult time identifying this plant. I now believe it is cotton grass (Calliscirpus criniger).

Scirpus, a genus in the Sedge Family, formerly had over 200 species including Scirpus criniger or cotton grass. Over the last 20 or more years Scirpus was divided into more than 50 genera. Scripus criniger became Eriophorum crinigerum. In 2013 Gilmour and Naczi using morphological, embryological and molecular studies showed that cotton grass was not related to either genus. They assigned E crinigerum the new appellation, Calliscirpus criniger. This new genus has two species, separated by and endemic to distinct geographical regions.

C criniger is found in the Klamath-Siskiyou Mountains and North Coastal Mountains of California and Oregon. Its habitat is wet meadows, streambanks, and seepage slopes on serpentine soils and rocks.

Cotton grass is a native perennial that grows from spreading rhizomes. This grass-like plant has a stem, like that of most sedges, that is triangular in cross section. The flat, linear, parallel-veined leaves are mostly basal and parallel-veined. The leaves feel rough to the touch (scabrous) because they are covered by small hairs. The solitary inflorescence is an umbel consisting of 5 to 10 closely clustered spikelets. The individual flowers are subtended by scales (bracts). Each flower has a one-celled, superior ovary and 1 to 3 stamens. As the plant matures the long, cottony bristles (modified sepals/petals) become more pronounced.

C criniger is also commonly called fringed cottongrass or cotton sedge. The genus name honors Tracey Gillette Call (1918 – 1994) and Viola Ruth Clifton Call (1920 – 2002), combining their last name with “scirpus”, the classical Latin name for a sedge. The species designation means “having or bearing hairs” from the Latin “crinis”.


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