And on the banks, on both sides of the river, there will grow all kinds of trees for food. Their leaves will not wither, nor their fruit fail, but they will bear fresh fruit every month, because the water for them flows from the sanctuary. Their fruit will be for food, and their leaves for healing.” (Ezekiel 47:12 ESV)
If the river is the gospel, then perhaps the trees are Christians planted by it, like the man in Psalm 1. He bears fruit in all seasons that feeds those around him. His leaves too are for the healing of the nations as he binds up the Brokenhearted. This is quite am image of the extent and the results of the gospel.