How Do Trees Produce Sap?

While you’re peacefully sleeping, you suddenly wake up to the sound of pots and pans. After a few minutes, you’re fully awake because of the delicious smell of pancakes in the air. You quickly get out of bed and head to the kitchen.

As you wait for your pancakes to be served, you start to think about where the syrup comes from. Similar to the paper you use at school, syrup is derived from tall, perennial trees. Yes, we’re talking about trees!

You can’t just drill a hole in any tree and expect syrup to come out. However, you can tap specific types of trees, like sugar maple trees, to collect sap during the right season.

Syrup makers use tree sap to create syrup. On average, it takes about 40 gallons of sap to produce one gallon of delicious syrup.

The sap inside a tree is similar to blood in the human body. It flows through a part of the outer tree trunk called sapwood, transporting water, sugars, and nutrients throughout the tree.

Sap production begins during the warm summer months when the process of photosynthesis produces carbohydrates that are stored in the tree as starch. The starch is then converted into sugar, specifically sucrose, which dissolves into the sap and is stored for the winter.

When spring arrives, usually around March, the weather conditions become ideal for sap production. These conditions include alternating freeze/thaw cycles, where temperatures drop below freezing at night and rise above freezing during the day.

During the day, the rising temperatures create positive pressure inside the tree, causing sap to flow out of any openings in the tree, such as taps specifically placed to collect sap, broken branches, or cracks. At night, when temperatures fall below freezing again, negative pressure develops inside the tree, halting the flow of sap. This negative pressure also pulls water from the tree’s roots to replenish the sap. Scientists believe these pressure differences are caused by the expansion and contraction of carbon dioxide gas within the sapwood.

This cycle continues until temperatures consistently stay above freezing, signaling the end of sap flow and the start of a new sap production cycle. Scientists believe that the main purpose of sap is to provide nutrients to new leaves as they grow, which in turn fuels the process of photosynthesis and initiates sap production.

You may be wondering if drilling holes in trees is harmful. When proper tapping procedures are followed, trees only sustain minor wounds that do not cause damage. Trees are capable of repairing drill holes and healing over time.

Give It a Try

Are you prepared to explore more WONDER? Enlist the help of a friend or family member to participate in the following activities:

  • Take a hike with a friend or family member in a local park or forest. Can you spot any sugar maple trees? If you’re unsure about what to look for, you can refer to How To Identify Sugar Maple Trees online. If you can’t find any sugar maple trees, make a list of the trees you are able to recognize. You can utilize a tree identification guide from a local library. There are also numerous online resources available. Capture pictures of the trees you come across, including their leaves, and then attempt to identify them when you return home.
  • Request an adult friend or family member to accompany you on a field trip to a local grocery store. What is your objective? Maple syrup, of course! Locate the syrup and count the different types of syrups available. In what ways are they similar? In what ways do they differ? Choose one syrup to try at home. You might also want to pick up some supplies to make pancakes or waffles. Once you’re back home, prepare a delicious breakfast with maple syrup as the main ingredient!
  • While you’re making pancakes, take the opportunity to observe and explore the process of changing states of matter! Visit the From a Liquid to a Solid – Making Pancakes lesson at the PNC Grow Up Great Lesson Center for guidance.

Reliable Sources


Leave a Reply

Your email address will not be published. Required fields are marked *