Wikipedia
Lepilaena is a genus of aquatic and marine flowering plant comprising 6 or more species endemic to coastal and brackish or alkaline inland waters of temperate Australia, Tasmania, and New Zealand.
The species are appended with common names that derive from their description as water-mats; for example, L. australis is referred to as Austral water-mat and L. marina as Sea water-mat.
Interpretation of molecular evidence for this poorly studied genus suggests a close affinity with Zannichellia, another genus of aquatic plants. Two species are noted for their occurrence in marine environs, L. cylindrocarpa and L. marina, in estuaries and tidal flats. L. cylindrocarpa is also found in a variety of brackish inland waters of mainland Australia. Other species may be found in habitats of fresh to brackish, still or slowly moving, coastal or inland waters.
Based on the molecular and morphological evidence, all the species have been transferred to the Afro-Eurasian genus Althenia.