Ruppia polycarpa
Leaves obtuse or acute, 5–10 cm long, usually less than 0.5 mm wide. Carpels 4–12 but usually 6–8. Peduncle at fruiting stage usually more than 10 cm long. Fruit slightly asymmetric, 2–3 mm long. Coast. Lakes and lagoons in brackish to very salt water and usually in water less than 1 mdeep. Fl. spring–autumn