Some foods give you gas, but March is the time of year when gas gives you a delicious food. Maple syrup, which is nutritious enough to be listed by the US Department of Agriculture as a food, is carbon dioxide-powered. If it wasn’t for a bunch of little gas bubbles in the wood or xylem tissue, maple sap would not flow. Who knew that trees were carbonated?
A mere two decades ago, biologists and arborists were at a loss to explain what causes maple sap to run. They’d typically mumble something about vacuum and straws before changing the subject. Everyone was aware that below-freezing nights followed by warm days led to sap flow. But it wasn’t until recent years that the mechanism behind sap flow was better – although still not perfectly – understood.