Syrup doesn’t come out of the tree ready made, obviously. Rather, syrup is made from tree sap. A lot of tree sap. It takes approximately forty litres (over ten gallons) of sap to make one litre (about a quarter of a gallon) of syrup. Considering that a tree can be tapped for only about 40-55 litres per season and yeah, now you understand why maple syrup is expensive.