Trichomanes javanicum

Trichomanes javanicum is a fern originating from South-East Asia, where it grows, amongst others, on the banks of rivulets. Its stiff leaves are dark green and slightly transparent, and it looks a bit like Bolbitis heudelotii. However, other than the latter, it does not form a creeping rhizome but a short upright shoot on which the rosulate leaves grow. The roots form mat-like structures on the substrate in nature.
T. javanicum is frequently sold under varying vernacular names like "Aqua Fern" in aquarium trade, unfortunately it cannot be cultivated submersed.