Oxycaryum
Oxycaryum cubense Nees
Synonym: Scirpus cubensis Poepp. & Kunth
Distribution: Introduced from Tropical America
Habitat: Ditches, seems to prefer eutrophic sites with standing algae-laden water
Florida status: Invasive exotic aquatic weed
Recognition: Heads globose, with long bracts. The achene covered with white bony material.