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Wetland Plants and Plant Communities of Minnesota and Wisconsin

GIANT BUR-REED

(Sparganium eurycarpum Engelm.)


Giant Bur-reed

BUR-REED FAMILY (Sparganiaceae)

IND. STATUS: OBL

FIELD CHARACTERISTICS: A stout, perennial herb, usually 0.5-1.5 m. in height. The inflorescence has zigzag branches and flowers in unisexual heads; the lower heads consist of the pistillate flowers which are bur-like at maturity, and the upper heads consist of staminate flowers. The pistillate heads are 2-2.5 cm. in diameter. Leaves are usually erect, 6-12 mm. wide, and strongly keeled so that they are flattened-triangular in cross section. However, ribbon-like floating and submerged leaves can also be produced (Figure 12). The mature fruit is 6-8 mm. long and square-topped with a sharp beak. In flower during June and July.

Giant bur-reed is our most common and robust bur-reed. It can be distinguished from all other bur-reeds because it has 2 stigmas and the fruit is nearly square across the top. The other bur-reeds have 1 stigma, and the fruit tapers to the base and apex.

At first glance, giant bur-reed may resemble cattail (Typha spp.) when not in flower; however, the strongly keeled leaves (flattened-triangular in cross section) of giant bur-reed will distinguish it from the flattened leaves (D-shaped in cross section) of cattail (Figure 13).

Stem and leaf cross sections
Figure 13 - Stem and Leaf Cross Sections

ECOLOGICAL NOTES: Giant bur-reed is a persistent emergent found in shallow water and on wet substrates in marshes, bogs and margins of lakes and streams. It is characteristic of silty, fertile waters, especially south of the vegetation tension zone, while other species of bur-reed (Sparganium spp.) characterize clean, low-nutrient waters primarily north of the tension zone.

Muskrats use the entire plant and the seeds are commonly eaten by waterfowl and marsh birds.

SOURCE: Fernald (1970); Gleason and Cronquist (1991 ); and Voss (1972).


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