Walk a stream bank in damp, shaded country. Look for something that does not belong among the ferns. The Water Fern spreads itself across the ground like a green tablecloth that forgot to stop. It occupies space with a casual confidence. The location is wet. The light is low. It thrives in these conditions without effort. Large fronds divide into broad, toothed leaflets. They are bright green and papery to the touch. The whole plant has a slightly floppy quality. It looks as if it has been watered too much. This is funny because it grows on stream banks, damp gullies, and open wet areas. It is not overwatered. It is exactly where it wants to be. The texture is soft. The appearance is unassuming. Do not let this fool you. The name incisa means cut into. Look at the leaflet margins. They are toothed. Serrated. Someone took scissors to this fern and kept going. The edges are sharp and distinct. This detail helps identify it among other large ferns. The structure is complex but consistent. Every leaflet follows the same pattern. It competes. That is what Water Fern does. It does not fight. It does not elbow. It simply grows faster than the things around it. It spreads by underground runners until the patch of ground belongs to it. Native plants lose. Gardeners often approve of its vigour. Conservationists do not. The spread is relentless. It claims territory by sheer volume of growth. The fronds can reach a metre long. That is a lot of fern. They arch and droop, creating a layered canopy. This shades out anything trying to grow underneath. This is not aggression. It is physics. No light means no competition. The plants below simply fade away. The Water Fern does not notice. It continues to expand. Remove it and it comes back. A fragment of runner left in the soil will regenerate. A piece of frond touching damp ground will root. Water Fern does not hold grudges. It just keeps growing. Persistence is its primary strategy. It waits for the right moment to re-establish. It rarely misses. In the right place, such as a wild gully, an unmown bank, or a corner of the garden you have given up on, it looks fine. It appears soft, green, and unassuming. In the wrong place, it is a quiet takeover. No announcement follows. One season it is a patch. The next, it is the whole bank. It has already won. No one told it otherwise.