On what TV series was Martin Mull's Garth Gimble impaled to death by an aluminum Christmas tree?

Martin Mull's character Garth Gimble was impaled to death by an aluminum Christmas tree in the TV series "Mary Hartman, Mary Hartman." This darkly comedic soap Opera, which aired in the 1970s, satirized suburban life and featured various absurd and surreal storylines. Gimble's death is one of the show's many bizarre and memorable moments.