Human beings around the world have harvested sweet tree saps for eons. Most of us in the Northern Hemisphere automatically think “maple” when we consider tree syrups, but in reality there are many other types of sap-giving trees. Birch trees, for example, which Alaskans and Scandinavians have long tapped for their sweet nectar. Hickory and elm trees also contain sap, though it’s less sweet and delivered in smaller quantities, so it takes more time and work to collect it and reduce it down to a syrup.
The process of making syrup from sap is a simple one: you simply boil it to evaporate off some of the moisture. Native Americans accomplished the task by heating rocks in a fire then — carefully — putting them in a bucket of sap. The process today is much the same in “sugar houses” on farms all around North America, only fire-heated cauldrons are usually employed.
Tree syrups are between 25% and 35% water, though more water is common since very dry maple syrup crystallizes easily due to all the sucrose it contains. As a general rule, you can assume a typical maple syrup is 2 parts sugar to 1 part water.