Plant Structure, Function, and Use
How is maple syrup harvested?
During the early years of colonial America, hemp (Agave sisalana)—a fabric that looks and feels like linen—was as common as cotton is now. It was an easy crop to grow, requiring little water, no fertilizers, and no pesticides. It was used for uniforms of soldiers, paper (the first two drafts of the Declaration of Independence were written on hemp paper), and as an all-purpose fabric—including Betsy Ross’s flag made of red, white, and blue hemp.
Maple syrup is harvested from the trunks of sugar maple trees (Acer saccharum). Production of maple syrup requires daily temperatures to fluctuate between freezing and thawing. During cold nights (below freezing), starch made during the previous summer and stored in wood is converted to sugar. During the day when temperatures rise above freezing, a positive pressure is created in the xylem’s sapwood. When a maple sap harvester drives tubes (called spiles) into the sapwood, the positive pressure pushes the sugary sap out of the tree trunk at a rate of 100 to 400 drops per minute—which is why around February in the northern regions with sugar maples, metal pails are often seen hanging from the trees. The flow stops when temperatures drop below freezing.