You might be amused if you heard me in the woods, with a cluster of kindergarteners around me, in early March. The conversation sounds something like this.
“Do you know what comes out of trees when we drill into them at this time of year?”
“Syrup!” Exclaim the enthusiastic children.
Not quite the answer I was looking for. I follow with, “Where does it come from?”
“Maple trees!” They cheer.
Back on somewhat more solid footing I respond, “Yes! But when we drill into maple trees, it is sap that drips out. It is not syrup yet! What is tree sap?”
The looks I get are blank, so I prompt, “Is it sweet? Do you think it has sugar in it?” A leading question, I know.
“Yes!” They decide, getting a bit wiggly and impatient to get on with this.
“So where does that sugar come from, the soil? The air? How does it get into the tree? Did you put sugar in this tree?” This elicits more blank looks and a few shy grins, as they detect that I am teasing them.
Then I tell them the most amazing thing: that trees, and all plants, make sugar – and the sugar in the sap was made in the tree leaves last summer, from sunshine . They look at me, not sure if I am teasing again or not, so I say, “I know it seems like magic, and really this is eighth grade science level, but it’s true! That is their superpower – the trees can change sunlight into sugars in their leaves and store it in their roots all winter.” We talk a bit more about sap, how it is mostly water and includes some minerals from the soil.
Then I ask, “Why does the tree store the sap in the roots all winter? What would happen if the sap was in the branches and twigs when it is cold out?”
“It would freeze,” they calculate.
“That’s right, and when water freezes, it expands and that could crack the tree and damage its buds, so the tree stores all the liquid in its roots instead. Why then, in the spring, does the tree move the sap up the trunk and into the branches?” I ask.
It takes a bit of conversation, but we get to the point: it is to feed the growth of buds and leaves. Ready to wrap this up I ask, “So does sap go up or down the tree trunks in the spring?”
“Down!” They say in unison and with committed certainty.
I see their teacher roll her eyes behind the line of students, but I did expect this, and I say, “I know, it is hard to believe, but trees have another superpower – they can move liquid sap up their trunks, without sucking it up!” This really is challenging to grasp because even kindergartners know that liquid never flows up. But trees use osmosis and capillary action to transport the sap.
I do not tell the kindergarteners this, but instead ask, “Have you ever dipped a napkin into a glass of water and watched the water move up towards your hand above the glass? It is like that. Trees can move water upward – all the way up to the tips of their branches.” To drive this point home, I show them the spile with a hole on the underside. “See, the hole for the sap is here, so when the sap flows up, it comes to this hole and drips out the spout.”
Then I ask, “Now we are ready to tap a tree – but how will we know which one? Can I get maple sap from this one?” And point to a nearby spruce. They agree, no, that one has needles.
“How about that one?” I ask, pointing to the trunk of a deciduous tree. They study it for a moment, unsure. So I say, “Do you see the pink color between the plates of the bark on this tree?” They nod, so I continue, “That tells me it is a red oak because they have that color. It is actually the color of the inner bark showing through in the fissures of the bark.”
I continue along the trail with them briefly and then stop to take a small sapling branch in my hand and draw their attention. “Do you see these twigs on this branch? See how they come off the branch like little arms, across from each other? This tells me it is very likely to be a maple tree! The only trees we have here that have opposite-branching branches like this are ash, which have big, thick twigs, and dogwoods, which are small trees and not big enough that we could tap them.” I turn and show them a large tree nearby, “So is this a maple tree? Do you see opposite branching branches?”
“Yes!” They know we have found a tree to tap. Everyone gets a turn to use the hand drill and they take turns tapping the spile into the hole. I show them the lid for the bucket and we talk about how animals in the forest love to drink sap, and how rain entering the bucket would dilute it. I put the lid on the bucket and ask one of the children to hang it off the hook below the spile. After he hangs it, he takes off his mitten and briefly strokes the tree – an apt and unsolicited gesture of appreciation.
The children will come back on a warmer day, when the sap is running, and taste it. They will cook maple syrup to sugar and taste its sweetness tinged with the minerals from the land. Those minerals were moved here by glaciers thousands of years ago and the sugar was made from sunlight that traveled 93 million miles in about 8 minutes 20 seconds to arrive at a leaf here, on the Pemaquid peninsula, last summer. These children are of this place, they too are made of well-traveled minerals and sunlight, and they thank the maple trees.
