What is the symbolic meaning of a leaf?

A single leaf is an ancient heraldic symbol that represents happiness. Leaves (together) have entirely different meanings though. The leaves of the oak trees are religious symbols of faith and endurance. Ivy leaves symbolize a strong and lasting friendship. This association is derived from its ability to stay attached to a rocky surface in even the most inhospitable conditions. Bay leaves, in ancient times, were considered remedies against poison, so they symbolize healing. Their image was also used as a symbol of tranquility. In contradiction, nettles (poisonous) are an ancient heraldic symbol whose leaves represent the sting of death to all foes. The burdock leaf, edock, or bur, was probably a symbol of tenacity and perserverance. The woodbine shows love that injures nothing to which it clings; it is also called honeysuckle and it is a climbing vine that doesn't damage the thing that it is attached to.