The heraldic banners of the schools of the University combine the colors normally used on the hoods of the various disciplines with symbols illustrating the activities of the histories of the disciplines, particularly at Stanford. The element which appears in all the flags is a triple frond of the redwood tree. By long usage, the Palo Alto redwood tree has been taken as the symbol of the whole University. The triple frond is used to symbolize the botanical function performed by leaves, namely the synthesis involved in the organization, transmission, and generation of knowledge which takes place in the schools and on which the scholarly growth of the University vitally depends. The common function of the schools is represented in the cardinal flag, the redwood frond in a white circle.