"And there shall come forth a rod out of the root of Jesse, and a flower shall rise up out of his root." (Isaiah 11:1)
Today's first reading is the primary biblical source for why the Messiah would come from Nazareth and be a Nazarene (that is, a flower); and also for the Jesse tree tradition.
Mary came as a shoot from the stump of Jesse, and Jesus is the bud that has blossomed from her.
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