Common bur-reed is a native perennial found in shallow water at the edges of rivers and marshes. It grows where water depth seldom exceeds 0.5 m and spreads by both seed and rhizomes. Itís the most common and
the most robust of the seven species of Sparganium in N. America.
Origin of the name: Sparganium, L., for bur-reed; eurycarpum, eury-, Gk., broad or wide; carpum, Gk., karpos, fruit
Range: Quebec to BC, s. to VA. OK, CA
WI Range: Statewide
Common associates: Iris, bulrushes, cattail, carices
Wetland Indicator Status: OBL
Coefficient of Conservatism: C = 6 (S&W), C = 5 (MI)
All Sparganium species have similar white or greenish flowers in dense round heads. The upper heads are staminate (male), the lower heads are pistillate (female) developing into bur-like fruit composed of many nutlets. Flowers bloom in June and July.
Mature nutlets are needed to determine the species of Sparganium except for S. eurycarpum. Its flowers have 2 stigmas, while flowers of the other species have a single stigma. The
nutlets are also distinctive in that they are broadest (5 to 8 mm) at the square tip, like an inverted pyramid.
Emergent leaves are erect, to more than 1 m long, and strongly keeled, so that they appear
triangular in cross-section -- unlike the leaves of Iris, which are flat, and Cattail, which are slightly D-shaped in section. Unlike most sedges, whose leaves are triangular and 3-ranked, the leaves of Sparganium are 2-ranked.