Wisconsin has eight species of cottongrass (Eriophorum).
All are native perennials with conspicuous cottony heads or spikelets and they grow in bogs. Tall Cottongrass and a very similar species, Narrow-leaf Cottongrass (E. angustifolium), are also found in fens
and in open areas of conifer swamps.
Origin of the name: Eriophorum: Gr., erio, wool; Gr., pherein, to bear or carry; viridi-carinatum: L., viridis, fresh green; L., carinatus, keeled. Refers to
the prominent mid-nerve on the scales.
Range: Nf. to BC, s. to CT, MN, WA
WI Range: Most common north of the Tension Zone
Common associates: Tamarack, white cedar, pitcher plant
Wetland Indicator Status: OBL
Coefficient of Conservatism: C = 10 (S&W), C = 8 (MI)
Cottongrasses are not true grasses but members of the sedge family. Sedges superficially resemble the grasses, since they have narrow leaves and inconspicuous flowers
without showy petals. Unlike the grasses, which have hollow stems, the stems of most sedges are solid. Grass flowers each have two tiny scales, while sedge flowers have only one.
Each of the
cottongrass spikelets contains many small flowers and each flower has many straight bristles. The bristles extend beyond the rest of the flower parts and elongate as the seeds form and mature.
Cottongrass grows to about 0.6 m and flowers in May and June.
Each stem has several drooping spikelets and 2 or more leafy green bracts that extend beyond the cluster of spikelets. The similar Narrow-leaf Cottongrass is distinguished by a band of dark red at the base of the cluster of spikelets and at the top of each leaf sheath where the leaf blade joins the stem. Tall Cottongrass has no red.