| Family | Scientific Name | Common Name | Habitat | Distribution | Image |
|---|---|---|---|---|---|
| Cymodoceaceae | Cymodoceaceae | Manatee-grass Family |  (c) Horn, Jay | ||
| Cymodoceaceae | Halodule | Shoal-grass |  (c) Montes de Oca, Joseph - CC-BY-NC, permission granted to NCBG | ||
| Cymodoceaceae | Halodule wrightii | Shoal-grass | Submerged in estuarine waters up to about 2 m deep, especially in Core and Pamlico sounds (North Carolina). | E. North Carolina, se. South Carolina (reported in 2021; not known from Georgia); Florida west to Texas, and south along shores of the Gulf of México and Caribbean; on the Pacific coast of Panama and Nicaragua; w. Africa. | (c) Montes de Oca, Joseph - CC-BY-NC, permission granted to NCBG |
| Cymodoceaceae | Ruppia | Wigeon-grass | (c) Horn, Jay | ||
| Cymodoceaceae | Ruppia cirrhosa | Spiral Ditch-grass; Widgeongrass | Lakes. | Wisconsin west to Alaska, south to Louisiana, Texas, New Mexico, Arizona, California, and Mexico; Central America, South America; Eurasia. |  (c) Keith, Eric - CC-BY-NC, permission granted to NCBG |
| Cymodoceaceae | Ruppia maritima | Widgeon-grass, Ditch-grass | Brackish estuaries, rivers, marsh pools. | Nearly cosmopolitan. |  (c) Bradley, Keith |
| Cymodoceaceae | Syringodium | Manatee-grass |  (c) Corder, Brandon | ||
| Cymodoceaceae | Syringodium filiforme | Manatee-grass | Estuarine waters. | Panhandle Florida, peninsular Florida, westward along the Gulf Coast to Texas, and along the Caribbean coasts of Mexico, Central America, and n. South America; 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. | (c) Corder, Brandon |