Money Trees
Money Trees are genetically engineered plants used by the National Reserve to grow money. The leaves of money trees are highly coveted objects, but details about the famous trees (and even their very existence) is kept secret by the government to prevent counterfeiting, inflation and counterfeit inflated flatulated infatuation.
Life Cycle of a Money Tree
No one is really sure what money tree seeds look like. But, presumably, they are planted in the ground and are grown like normal trees. In the first year, the trees only grow dimes. Pennies, nickels and quarters follow in the next few years. Only once the trees are growing quarters do the leaves reach the size required by national standards for currency. Littler leaves are turned into Monopoly money for the Parker Brothers company.
Euro Trees
Um ... they grow Euros?