By Harold McGee
The maple family originated in China or Japan and numbers some 100 species throughout the Northern Hemisphere. Of the four North American species good for sugaring, the hard or rock maple, Acer saccharum, produces sap of greater quality and in greater quantity than the others, and accounts for most of the syrup produced today. In the spring, sap is collected from the first major thaw until the leaf buds burst, at which point the tree fluids begin to carry substances that give the syrup a harsh flavor. The sap run is improved by four conditions: a severe winter that freezes the roots, snow cover that keeps the roots cold in the spring, extreme variations in temperatures from day to night, and good exposure to the sun. The northeastern states and eastern Canadian provinces meet these needs most consistently.