Gal-en-du'un

Found on Vulcan's volcanic plains, gal-en-du'un is a yellowish-green lichen, and when consumed (either by ingestion or by burning it and breathing in its fumes), it causes strong hallucinations which last several minutes in duration. "Dream moss" was used in ancient times by ecstatic priests to induce revelatory visions. Interestingly, its effect on Vulcans is much stronger than its effect on humans. Its modern uses are restricted to medicine, as a number of Vulcan analgesic and neurochemical treatments use gal-en-du'un essence.