| Family | Scientific Name | Common Name | Habitat | Distribution | Image |
|---|---|---|---|---|---|
| Cymodoceaceae | Cymodoceaceae | Manatee-grass Family |  | ||
| Cymodoceaceae | Halodule | Shoal-grass |  | ||
| Cymodoceaceae | Halodule wrightii | Shoal-grass | Submerged in estuarine waters up to about 2 m deep, especially in Core and Pamlico sounds (North Carolina). | E. NC, se. SC (reported in 2021; not known from GA); FL west to TX, and south along shores of the Gulf of México and Caribbean; also on the Pacific coast of Panama and Nicaragua. | |
| Cymodoceaceae | Ruppia | Wigeon-grass | | ||
| 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. |  |
| Cymodoceaceae | Syringodium | Manatee-grass |  | ||
| Cymodoceaceae | Syringodium filiforme | Manatee-grass | Estuarine waters. | Panhandle FL, peninsular FL, westward along the Gulf Coast, and in the West Indies. Syringodium is occasionally cast ashore in Georgia and the Carolinas following hurricanes, but there is no evidence that it grows along the Atlantic coast north of Florida. | |