Potamogetonaceae >

Inflorescence always 2-flowered. Carpels 2–19. Mature fruit usually stalked Ruppia

Peduncle at fruiting stage coiled several times. Flowers floating or close to the water surface. Fruit submerged

Leaves truncate or emarginate, 5–15 cm long, 0.5–0.8 mm wide. Carpels 2–6 usually 4. Peduncle at flowering more than 15 cm long. Fruit brown-black, asymmetric, 3–4 mm long; fruit stalk often reflexed. Coast. Lagoons and estuaries in brackish to very salt water. Fl. spring–autumn Ruppia megacarpa