This Jesus is the "Rod of Jesse". The full meaning of this expression becomes clearer when we go back to the Hebrew text of the entire passage: "And there shall come forth a shoot from the stump of Jesse, and a sapling from its roots shall bear fruit". The emphasis of the text is evidently on the difference between humble beginnings and a glorious end.
Note: All of these symbols can be seen on the outside walls of the Hesburgh Library.