St. John Cathedral Oak – #33 or original 43 Live Oak Society member trees. The St. John Cathedral Oak is located in Lafayette, Louisiana on. The Seven Sisters Oak is the largest certified southern live oak tree. Located in Mandeville, Louisiana, it is estimated to be up to 1, years old with a trunk that. species, and the tree appears to be an alternate type. Oak and hickory trees hybridize readily and the A few Louisiana tree species have leaves almost.