Bulrush is a group of grasslike plants that grow in marshes or in shallow water. They have tough stems that are round or triangular and up to 12 feet (3.7 meters) tall. Their tiny flowers are clustered into small brownish spikelets at or near the tops of the stems. Mats may be woven from the stems. They also furnish raw materials for thatch, boats, and houses. The seed is an important food for wild ducks. See also Sedge .