Brinevine

The brinevine is a mound of inviting grasses that looks like a nice dry place to rest while traveling through The Thrundank swamp, but its a trap.
Hidden underneath in the water, are vines that attack those who have settled upon it.
The vines drag their victims down to the underside of the mound where a great thorny maw closes about them, pinning them in a prison until its roots drains all fluids from the victim.
Once a victim is drained, the thorny maw spits it out and opens to wait for the vines to bring it another.
Brinevines start out as tiny mounds feeding on frogs, turtles, and birds.
They do not stay tiny. The longer one lives, the bigger it gets.
As it grows, it grows more maws and vines as well. The biggest ones can hold several people on their nice grassy tops.

Brinevine Looking Harmless by Natalia_Kollegova