Ultherus Swamp

The Ultheus Swamp is a place in Black Marsh where a lethal, fernlike herb called Dragon's Tongue grows.

Dragon's Tongue
Dragon's Tongue, a common name for a fernlike herb found in Black Marsh, is especially prolific around the area of the Ultherus Swamp. It is a beautiful wildflower whose name comes from the fire red fronds that protect its golden efflorescence. As pretty as it is, however, it is a deadly poison to most beings and needs to be avoided by adventurers, especially unprotected ones, as it is lethal to the touch.