Who is The Bursar from The Last Continent: A Discworld Novel and what is their importance?

The Bursar is one of the faculty members of Unseen University (UU) who in their search for their colleague Rincewind enter a tropical island thousands of years in the past and make their way to the continent of Fourecks. The unnamed Bursar is severely mentally unstable and takes no part in his colleagues' preoccupation with Mrs. Whitlow's sexuality. He hums randomly and recalls irrelevant facts. Badly in need of dried frog pills, which cause him to hallucinate that he is sane, the Bursar wanders off into the jungle and follows a trail marked by a strange throbbing stem.