On Food and Cooking

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.
Sap does run in other trees in early spring,
and some of them — birch, hickory, and elm,
for example — have been tapped for sugar.
But maples produce more and sweeter sap
than any other tree, thanks to an intricate
physical mechanism by which the tree forces
sugars from the previous growing season out