bur reed

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of various aquatic or wetland plants of the genus Sparganium, having elongated leaves and ball-like clusters of tiny beaked fruits.

Century Dictionary and Cyclopedia

1. n. The common name of species of Sparganium, so called from their narrow, reed-like leaves and bur-like heads of fruit. The floating bur-reed is S. angustifolium. See Sparganium.

GNU Webster's 1913

1. n. (Bot.) a plant of the genus Sparganium, having long ribbonlike leaves.

WordNet 3.0

1. n. marsh plant having elongated linear leaves and round prickly fruit