large species having three ridges on its back; found in southeastern United States

prolific South American aquatic weed having grasslike leaves and short spikes of white flowers; clogs waterways with dense floating masses

prolific South American aquatic weed having grasslike leaves and short spikes of white flowers; clogs waterways with dense floating masses

prolific South American aquatic weed having grasslike leaves and short spikes of white flowers; clogs waterways with dense floating masses

prolific South American aquatic weed having grasslike leaves and short spikes of white flowers; clogs waterways with dense floating masses

prolific South American aquatic weed having grasslike leaves and short spikes of white flowers; clogs waterways with dense floating masses

a wrench with a v-shaped jaw and serrations on one side (resembles the open jaws of an alligator)

a wrench with a v-shaped jaw and serrations on one side (resembles the open jaws of an alligator)

a wrench with a v-shaped jaw and serrations on one side (resembles the open jaws of an alligator)

a wrench with a v-shaped jaw and serrations on one side (resembles the open jaws of an alligator)