Guardians

The City of the Lost was build at both sides of the river, near to the unexplored area of the forest; they had a lot of issues with the dangerous creatures that lurked under the water.
When a community of carnivorous plants started growing in the bottom of the river, they were happy to let them keep doing that. The community has grown a lot since then, and the river is safe in all the City's territory. Nowadays, there isn't a lot of food for the carnivorous plants in this area, the hunt is better in the City's border. The walls were built by the managers of the terminal, but reinforced by the shards overnight. Nobody knows if the vegetal guardians are here for the free food or because the shards sensed the fear of the sailors.
Discovery
For years, the idea of using the river as a mean of transport, wasn't even contemplated, but at some point a sailor that has lost his whole crew due to his and their recklessness, moved in. It took him a while and he almost got killed a few times, but he ended up finding the right weapons and a good way to repel the creatures while he traveled. The boats would be damaged by the same things that kept the sirens away, but that wasn't too bad in a place with plenty resources.
The only thing that still bothered him, was the risk of being eaten as he delivered his cargo. But he noticed that that wasn't an issue in the dock of the City's terminal. At first he thought that the city was free of pesters, but he soon discovered that that wasn't the case. The Swamp was getting more and more safe, but the rest of the city had learnt to avoid the the river's predator.
Out of curiosity, he kept investigating, observing, until he discovered that even the worse of those nightmarish creatures was considered prey by the giant plants that grew under the water.

Basic Information

Anatomy

One strong wide and sticky root adheres itself to a surface or digs into the bottom of the river, keeping the rest of the plant in place. It has the conductive properties of other roots, and it may be used to get some nutrients from the water or the soil.
The thinner roots are the ones that enter under the skin of their prey, while the big complex flower is probably the one attracting them.
The flowers show different color and texture depending on the area, or vary from plant to plant.

Additional Information

Perception and Sensory Capabilities

They rely in a sense that shares characteristics of both taste and touch, which allows them to perceive the creatures that are near and their movement, by interpreting the conditions of the water.

Discovered by

Iludio Nai, a boat's captain

Also know as

Nightmare’s eaters
Keepers

Social structure

They don't seem to be rational beings, yet the collaborate to close the way out of any river monster one of them had decided to eat.

Personality

Is it a coincidence that they eat creatures that cause trouble wherever they go? Do they care for the fate of other creatures in, or near, the river? Maybe they are protective, maybe they are just hungry.
Whatever may be the truth, many think they are "nice and kind" and there are plenty of stories about them changing their flowers to feed an orphan or make someone smile.

Intelligence

They don't seem to be rational nor do the show intelligence in the sense we give to that word.