arries water and nutrients from the roots to the rest of the tree. The phloem tissue carries the sugars produced by photosynthesis from the leaves into the base of the tree. “ When the maple trunk thaws out in early spring, it appears that the specialized xylem cells actively pump their sugar into the xylem vessels, the transport tubes formed by now-dead cells.” (Pg. 384). There are two effects from this process. One is that the increase in sugar content of the xylem vessels creates an osmotic pressure that draws water into the vessels, thereby increasing the water pressure. The second is that the metabolic activity of the working cells, releases waste product, like carbon dioxide. The solubility of CO2 in water decreases as the temperature rises above zero degrees Fahrenheit. As the trunk warms on a sunny day, gas pressure builds in the xylem along with water pressure. The result is a great sap flow outward when the xylem is tapped. This old sap is pushed out to make way for the New Year’s product.The production of syrup has varied from generation to generation. The Native American technique was that of cutting a wide gash within the trunk, though this could not have been done in the same tree year after year. The colonists would punch a small hole in the tree, fitting it with a metal spout and bucket to collect. The sap was then boiled and depouillaged of impurities. The final concentration was high enough that the syrup would usually solidify to crystals.Sinkovitz, pg. 3Today, the trees are tapped with a power drill, and tubes are run from a holding tank to the “sugarbrush” or stand of maples. “ The concentrating process is controlled by monitoring the boiling temperatures and density of the syrup, both of which are determined by the sugar concentration.” (Understanding Baking, pg. 58). The original sap contains about 3% sucrose, while one tree may yield 12 gallons of sap in one season. For e...
