Maple sap is thin, barely sweet, and as colorless as spring water. The distinctive maple taste comes only through boiling. The sugar in the sap is a bit of a mystery. It seems that each fall, the tree produces its own supply of starch to act as an anti-freeze for the roots in winter. With the melting of snow, water enters the root system and begins the circulation of 'sugar water' through the tree in preparation for the growing season. As a result, the sweet sap runs freely from the first spring thaw until the buds turn into leaves from mid-March until April.