"The path winds beside the lake shore past stands of reeds and floating lilies. Here and there the path turns into a patch of mud and leaves. Suddenly, you are brought to an abrupt halt by the sound of hissing and rattling that comes from a patch of segmented reeds that overgrows the path."
This is a patch of snake grass. This weird animated grassy reed bears the tiny head of a snake at its tip that hisses and curls its tongue at intruders. Anyone trying to cut a path through them will be attacked by the elongating reeds. Every time 5 points of damage is inflicted, a reed will be severed and another segment will be revealed beneath with another snake head. The snake grass injects a weak poison that causes a cumulative -1 penalty to all rolls for one day. Save vs. poison at -2 for no damage. There are 18 reeds.
Originally appeared in I13 - Adventure Pack I (1987).
How is their "multiple heads" supposed to work? The wording is rather confusing, but I'm guessing they mean that it grows an additional head every time it takes 5 or more damage.
Hmm, or by medusas. Well, I'm pretty much up in the air among the three options. I guess aberration is slightly ahead of plant, but I don't mind much either way.