Sugar Maples

The maple syrup on your French toast and those yummy maple syrup candies seen around the holidays are tree sap.

Sugar maple leaves (Superior National Forest) CC BY 2.0

Sugar maples (Acer saccharum) are related to soapberries and lychee. These deciduous hardwood trees create glorious fall foliage before winter sets in. As temperatures rise, trees convert the starches stored over the winter into sugary sap. That sap starts rising through the phloem to feed new growth. That’s where we step in.

Sugar maple tap and bucket (Wagner2005) CC BY 3.0 DEED

Many years ago, in Stafford, Virginia, I opened a private K-12 school called Children’s Academy. We had a silver maple tree on the property, so we decided to try our hand at tapping it. Tapping trees refers to the way we get to the sap. Taps, also known as spiles or cask pegs, used to be hand-carved wooden tubes, but modern taps are metal. Taps are hammered into the tree to reach the phloem, just under the bark, where the sap flows.

Maple description

Most of us are familiar with hand-shaped, pointy maple leaves. These trees can get quite large, growing 80 feet tall or more. The bark is a lovely pale gray. The greenish-yellow flowers do not have petals. Instead, they grow in several panicles, clustered together, usually after 30-55 growing degree days. The fruit grows in winged pairs that most of us called ‘helicopters’ because they spin as they fall. Those fruits are called samaras, and they contain maple seeds.

Sugar maple tree (Bruce Marlin) CC BY-SA 2.5

Sugar maple bark (Derek Ramsey) CC BY-SA 2.5

A pair of samaras (Steve Hurst @ USDA-NRCS PLANTS Database) Public Domain

Other maples

Sugar and black maples (Acer nigrum) are the primary sources of maple syrup, but our silver maple did well enough. Other maples, including our silver, have lower sugar levels and produce a cloudy (but still delicious) syrup. Norway maples are quickly taking over suburban streets because of their ability to withstand air pollution and weather fleck better than sugar maples. Unfortunately, they are not good sources of sap. One way to tell which maple tree you have is to look at the sap in a leaf petiole. Sugar maple sap is clear. Norway maple sap is white.

How maple trees grow

Maples love cold winters and are best suited to USDA Hardiness Zones 3-5. They take 30 years to reach seed-bearing age and live 200 years or more. These trees are very shade-tolerant. They are best planted as saplings in the spring or fall in well-draining soil. They prefer slightly acidic soil but can grow in soil pH levels of 5.0—7.0.

Sugar making in Montreal, October 1852 by Cornelius Krieghoff (artist); Sarony & Major (engraver) Public Domain

How to make maple syrup

Sap was traditionally boiled over an open fire for a very long time to get rid of the excess water. But it takes, on average, 40 gallons of sap to make one gallon of syrup. Collecting sap is very labor-intensive, and all that cooking uses a lot of energy, so now you know why maple syrup is so pricey. Compounding that problem is the maple tree’s sensitivity to air pollution.

Maple tree decline

Starting in the 1950s and culminating 40 years later, a drastic decline in Canadian sugar maples was considered a serious threat to the species (and global maple syrup supplies). Acid rain was killing all the sugar maples in Canada and the northeast US. So Canada and the US created The Canada – United States Air Quality Agreement in 1991. By 2023, the actions outlined in that agreement resulted in a significant decrease in the chemicals responsible for acid rain and sugar maples started to recover. [See what we can do when we work together?]

Did you know that the samaras can be soaked, boiled, seasoned, and roasted (without the wings) for a yummy snack? I didn’t either.

Now we know.