Give Now

A Moment of Science

Sweet Sap: What Exactly Is Maple Syrup?

Why do sugar maple trees produce sweet sap?

5 jars of freshly made maple syrup

Photo: Kevin (Flickr)

For the best maple syrup, there should be a sunny summer and fall with a late frost.

If you take a spring walk through the woods in many parts of the Northeast, you’ll find buckets hanging from the sides of maple trees. Drop by drop, the buckets are filling up with the slightly sweet sap from the trees. When that sweet liquid is boiled down, it becomes maple syrup, all ready for a plate of pancakes.

Sweet Syrup

Colonists arriving from Europe learned from the American Indians how to tap maple trees and boil the sap into syrup. For a long time, maple syrup was the only concentrated sweetener available on this continent.

Photosynthesis

Today, little is known for certain about why a sugar maple produces such sweet sap. The sugar in the sap is made in the leaves by photosynthesis — the same process that all green plants use to convert water, sunlight, and carbon dioxide into food.

Getting The Best Sap

So the best year for maple syrup is one with the best conditions for photosynthesis — a sunny summer and fall with a late frost. A cold winter and a heavy snow fall to keep the roots cool in the spring also improve the syrup harvest.

And any year with extreme variations in temperature from night to day tends to be a good year for maple syrup as well.

Do Other Trees Produce Sugars?

All trees produce some natural sugars, which they use for energy in their own growth processes, but not all trees, or even all maples produce enough or the right kind of sugar to make syrup.

Out of about 100 species of maple trees, only four are good for syrup and of those, one species — the rock, or hard, maple — produces most of the syrup we use.

If you’re wondering why something that flows from trees should be so expensive, consider how little syrup you get when the sap is boiled down. The pint jug of syrup you buy in the store came originally from about five gallons of sap.

Stay Connected

What is RSS? RSS makes it possible to subscribe to a website's updates instead of visiting it by delivering new posts to your RSS reader automatically. Choose to receive some or all of the updates from A Moment of Science:

Support for Indiana Public Media Comes From

About A Moment of Science

Search A Moment of Science