Mergrass

Mergrass was a species of tough and tall water-loving plants.
  Often found in the swamps and around lake in Thalgriel
  Mergrass was known for its hard reeds that rose hight up from the water-submerged roots. This plant was used as a building or crafting material and often sold in bundles worth fifteen gold coins.
  Refined alchemical suspension of mergrass was the primary component in brewing a variant of the potion of mind reading. Even a slightest touch of mergrass suspension to the imbiber's lips made them hear subdued bursts of sound – pulses of thoughts of nearby creatures.