USS Arizona, one of the two bells rescued from the ship after the attack on Pearl Harbor, has a permanent home in the clock tower of the Student Union Memorial Center. The bell arrived on campus in July 1946. The bell was rung seven times on the third Wednesday of every month at 12:07 pm – symbolic of the battleship's sinking on December 7, 1941 – to honor individuals at the UA, as well as after home football victories, over any team except other Arizona schools. In December 2020, it was announced that at the request of the U.S. Navy, who still officially owns the bell, and in the interest of preservation of the historic artifact, that the bell would no longer be rung. The Arboretum at The University of Arizona Much of the main campus has been designated an arboretum. Plants from around the world are labeled along a self-guided plant walk. The Krutch Cactus Garden includes the tallest Boojum tree in the state of Arizona. Two herbaria on the university campus are referred to as "ARIZ" in the Index Herbariorum The campus also boasts hundreds of olive trees many of which were planted by Prof. Robert H. Forbes. Many of these trees are over a hundred years old. Organization The University of Arizona, like its sister institutions Arizona State University and Northern Arizona University, is governed by the Arizona Board of Regents or the ABOR, a 12-member body. Eight volunteer members are appointed by the Governor to staggered eight-year terms; two students serve on the board for two-year appointments, with the first year being a nonvoting apprentice year. The Governor and the Superintendent of Public Instruction serve as voting ex-officio members. The ABOR provides "policy guidance" and oversight to the three major degree-granting universities, as provided for by Title 15 of the Arizona Revised Statutes. Robert C. Robbins, M.D., was named the 22nd president of the UA on March 7, 2017. He began his term on June 1, 2017. Previously, he was the president and CEO of Texas Medical Center in Houston from 2012 to 2017. In prior roles, Robbins was professor and chairman of the Department of Cardiothoracic Surgery at Stanford University School of Medicine, founding director of the Stanford Cardiovascular Institute, president of the International Society of Heart and Lung Transplantation and president of the Western Thoracic Surgical Association. Robbins replaced Ann Weaver Hart, M.A., Ph.D.,