Ruppia L.
Inflorescence always 2-flowered. Carpels 2–19. Mature fruit usually stalked Ruppia
Peduncle at fruiting stage not coiled or loosely coiled 1–2 times. Flowers submerged. Fruit black, 2–3 mm long, asymmetrical, with stalks c. 1 cm long. Leaves linear, up to 5 cm long, c. 0.5 mm wide, with an acute or obtuse tip. Coast. Estuaries in brackish to very salt water. Fl. spring–autumn Ruppia maritima
Peduncle at fruiting stage coiled several times. Flowers floating or close to the water surface. Fruit submerged