Many varieties of plants and trees are used symbolically throughout the bible. Palm branches are most often used as a symbol of Jesus' triumphal entry into Jerusalem, the event that heralded his coming Passion and crucifixion.
By derivation, palms may represent the fickleness of human acclamation. Used by the Romans as a symbol of victory, they have been used by the church as a symbol of Christ's ultimate victory over sin, or of the saints' victory over death. Therefore in art history martyrs are sometimes portrayed holding palm branches and the branches were used as a funerary emblem among the early Roman Christians.
How will your congregation celebrate with palms this Palm Sunday?