The basis of the Jesse Tree is a prophecy of the coming Christ in Isaiah 11: 1-10 :
 There shall come forth a shoot from the stump of Jesse,and a branch shall grow out of his roots.
 And the Spirit of the LORD shall rest upon him, the spirit of wisdom and understanding,the spirit of counsel and might,the spirit of knowledge and the fear of the LORD.
 And his delight shall be in the fear of the LORD. He shall not judge by what his eyes see, or decide by what his ears hear;
 but with righteousness he shall judge the poor, and decide with equity for the meek of the earth; and he shall smite the earth with the rod of his mouth, and with the breath of his lips he shall slay the wicked.
 Righteousness shall be the girdle of his waist, and faithfulness the girdle of his loins.
 The wolf shall dwell with the lamb, and the leopard shall lie down with the kid, and the calf and the lion and the fatling together, and a little child shall lead them.
 The cow and the bear shall feed; their young shall lie down together; and the lion shall eat straw like the ox.
 The sucking child shall play over the hole of the asp, and the weaned child shall put his hand on the adder's den.
 They shall not hurt or destroy in all my holy mountain; for the earth shall be full of the knowledge of the LORD as the waters cover the sea.
 In that day the root of Jesse shall stand as an ensign to the peoples; him shall the nations seek, and his dwellings shall be glorious.
This prophecy is recalled in Romans 15:12
"The root of Jesse shall come, he who rises to rule the Gentiles; in him shall the Gentiles hope."
So who's Jesse? Jesse was King David's father and Jesus is descended from the line of King David. Throughout Advent, we hear reference to Christ's ancestors in the Mass readings.
In the Church, depiction in art of Christ's royal lineage is quite old; the West facade of Chartres Cathedral, dated to ca. A.D. 1150, has a window that depicts the "Tree of Jesse" . In fact, the Jesse Tree has been depicted in almost every medium of Christian art.
In the home, a Jesse Tree is a collection of images or symbols hung on a branch or tree to show the history of Christ's coming. There no one right way to do a Jesse Tree in the home. Some like to stress the prophecy, others the history, all with the aim of showing that Christ has sprung from the root of Jesse and come to save us.
If you aren't accquainted with the Old Testament as much as you'd like to be, Advent is a good time to change that. The Old Testament shows us how God has Fathered His people throughout history and how Christ fulfilled the Father's promise in establishing the new covenant.
A Jesse Tree in the home can be a great catechesis tool.
I'm offering some simple cut and paste (real life cutting and pasting that is) ornaments for a Jesse Tree that start with December 1st and includes the seven Great O Antiphons.
A Blessed Advent to you and yours!
*The Jesse Tree is an Advent teaching tool and liturgical year actitvity that is a private devotion. It is not required for a successful or holy Advent.