Ruppia polycarpa
Ruppia polycarpa is a submerged aquatic herb species in the genus Ruppia found in shallow brackish waters. It is a common submerged herb on Australasian coasts, including Australia and New Zealand.
It was first described in 1967 by Ruth Mason from a specimen found near the mouth of the Selwyn [River / Waikirikiri|Selwyn River], New Zealand, on the riverbed, on 27 February 1966 by J. Clarke.
It grows in "fresh to hypersaline coastal lakes, lagoons and estuaries".