| Family | Scientific Name | Common Name | Habitat | Distribution | Image |
|---|---|---|---|---|---|
| Cymodoceaceae | Ruppia cirrhosa | Spiral Ditch-grass; Widgeongrass | Lakes. | WI west to AK, south to LA, TX, NM, AZ, CA, and Mexico; Central America, South Americal Eurasia |  |
| Cymodoceaceae | Ruppia maritima | Widgeon-grass, Ditch-grass | Brackish estuaries, rivers, marsh pools. | Nearly cosmopolitan. |  |