Some of the mezuzahs I make come to you with the bark attached and others arrive bark free. But why?
In the winter, when the tree is dormant, there is no activity in the cambium, an area one cell thick right below the bark. The sap is not yet rising.
But during the rest of the year, the tree is busy making growth rings. Amazingly, water is pulled up through the sapwood by evaporation in the leaves or needles. The sap is rising! It flows back down through the cambium layer, where the cells are dividing.
If a branch dies in winter, the bark remains attached. It is stuck to the wood by the dried juice of last year’s growth.
During the growing season, the cambium is active and wet and If a branch breaks off now, or dies on the tree, the bark will be loose and eventually fall off.
Towards the end of winter my good friend Héctor and I spent several Sunday mornings hiking in the foothills of the Sandia mountains outside of Albuquerque. On one hike we came across a downed piñón tree. I pulled out my trusty folding pocket saw and accepted the gift of a few branches.
The bark stayed on because the tree had died in winter
On another Sunday we found some branches under a living tree. The bark was loose on these branches. They had been broken off during the growing season.
The beloved piñón is the state tree of New Mexico. It grows so slowly that it can take several hundred years before its trunk reaches a diameter of only four inches. Traditional Santeros still make their varnish using sap from the piñon tree, a recipe that dates back to the 1600s. Squirrels, jays, bears, deer and people covet the divine nut it produces only every two to seven years. The fragrance of the tree is also divine and unforgettable.