Although you can eat several types of tree sap, you should not start gnawing on every tree trunk you see. Some trees produce bitter or even poisonous sap. Plus, even edible sap licked directly from the tree is not very tasty. However, the next time you drizzle maple syrup on your waffles, just remember that it comes from tree sap.
The best-known form of edible tree sap is that of the maple tree. The sucrose-rich sap is so sweet and tasty that it is a feature of breakfasts and snacks across North America and many other parts of the world. Experienced maple tappers can collect as much as 80 gallons of sap from one tree in a year. You need 10 gallons of fresh sap to make a quart of syrup, according to the University of Maine Extension.
Sap from the birch tree is edible, though tapping only tends to occur in cold states such as Alaska or parts of Canada. The sap is a clear sticky liquid that turns more yellow when reduced on the stove. You can use it as a breakfast syrup, though it's less sweet and rich than maple syrup. The syrup provides a range of nutrients, including fructose, glucose, amino acids, vitamin C, potassium, calcium, magnesium, zinc, sodium and iron, according to the University of Alaska Fairbanks. Unlike maple sap, birch sap doesn't contain the disaccharide sucrose.
When you were young and playing outdoors, it's likely that adults reminded you of the saying, "Leaves of three, let it be." This applies to avoiding the sumac family of plants and trees, whose most familiar members are poison ivy and poison oak. The sap of both these plants is poisonous and can trigger nasty skin reactions and even anaphylactic shock in some people. The Florida University School of Forest Resources and Conservation also points out that burning sumac wood can release toxic fumes.
The safest option if you don't recognize the species of a wild tree is to avoid eating any fruit or sap. Even edible sap such as maple tree sap needs to be reduced by boiling before it makes a thick, delicious syrup. Boiling also gets rid of any impurities and bacteria that may be hiding within the gooey sap. If you have a strong reaction after eating any tree sap, particularly if you notice breathing difficulties, seek medical help immediately.