Tree sources of syrup include MAPLES, which are deciduous trees that are native to North America and parts of Asia. MAPLES produce a sweet sap that can be boiled down to make maple syrup. Other tree sources of syrup include birch, walnut, and hickory. Birch syrup is made from the sap of birch trees, while walnut and hickory syrup are made from the sap of walnut and hickory trees, respectively. All of these syrups are popular alternatives to maple syrup and are used in various recipes.