Heartwood

There is much to be learned from the inside of a tree. The lessons begin with its colors, distinguishing the heartwood, which is dark, and the sapwood, which is light. The one for stability and the other for nourishment. The yin and yang of constancy and growth, pause and movement, stasis and change.

But such a distinction is a bit misleading, for it makes us think that each wood is created as one or the other from the start, just as we are created male or female from birth, or parts of our body are created muscle or bone. But that is not the way it works with wood.

Wood changes. The heartwood, the solid core, begins as sapwood, the fleshy rim. The softer sapwood's destiny is to become, in due time, the hardened heartwood.

Sapwood grows anew each year, porous and pliant, allowing water and nutrients to travel from root to leaves and back again. When the tree is young and hungry, all its wood is sapwood. Supple, flexible, fluid it responds to the lusty demands of youth.

Youth enjoys and needs voluminous energy; an abundance of freedom; an exaggeration of movement. It is a time of impulsiveness, vulnerability, enormous appetites for tasting the world. (I still speak of trees here though there definitely seems to be a slippage into the realm of people!)

But as the tree grows, its needs change. Height and maturity demand structure, something reliably solid, fixed, and dependable. An overabundance of sapwood would make the tree bloated, grotesquely voracious, a doughy blob that clogs and strangles itself through excess consumption.

So the wood changes, morphs, in response to two needs: a reduction in the proportion of nutrient consumption and an increase in the demand for structural support. The sapwood turns into heartwood, apparently rather abruptly (the line between the two is narrow and distinct), moving from consumption mode to stasis mode, as inexorably as children turn into teens and teens turn into adults. (Sometimes the change in people is as surprisingly rapid. Other times, not.)

But something even lovelier happens. Moving from sapwood to heartwood is not just a process of hardening; it is a process of beautifying and strengthening. The chemicals and "extractives" that accumulate in the sapwood transform the wood in two additional ways: they protect it from decay and infestation, offering a defense against disease and decay; and they confer upon it its classic coloration. Cherry, walnut, oak all get their coloration, their distinctive beauty, from this process of maturation.

This aging, this hardening, this dying of sorts, is not an aspect of decrepitude or decline, but a necessary part of health for the organism as a whole.

I had planned to write on this topic today anyway, but the thoughts here gained greater urgency and intensity when I learned that my sister-in-law's father passed away yesterday.

He was a fun man, one of those fellows with a bottomless satchel of jokes, riddles and puns. And he was a man of great accomplishment, although he was too modest to let you know. He helped invent memory wire, an invaluable material in medicine and space industries, never mind costume jewelry!

His aging was difficult, his death a true loss. And yet his life, his legacy, his memory serve as our heartwood. His sapling years gave us much novelty and growth, but they are now gone. Still, his heartwood years live on. I know my sister-in-law and her family remain buoyed and steadied by the strength this core offers. How wise that it is called heartwood.

(the photo above is a cross-section of the tulip poplar we had to take down)