Black Cottonwood: balm or bomb?

Black Cottonwood (Populus balsamifera ssp. trichocarpa)

Is the silent juggernaut over? Is the Cottonwood bombing at an end? Can we get back to tending our fields and flocks again? For days now we have been under attack by the annual Cottonwood blizzard. The Cottonwood trees have unleashed wisps of snow-flake-like fluff by the tens of thousands on our poor nursery plants. Trapped in their little pots, nowhere to go, surrounded by bare soil, our chlorophyll-babies are defenseless against the relentless germinating power of a pioneer species seeking new horizons, new places to plant itself. Though we do grow some to be planted in restoration projects, we don’t really appreciate 30 extra trees in every pot in the nursery!*

Black Cottonwood is one of those native plants that doesn’t get much respect. “Junk tree” is what loggers call it. It isn’t even any good as firewood; the water content is so high that it barely cures enough to provide a few BTUs on a winter’s day. It is widely known as a “hazard tree” because of the huge branches that it occasionally sheds. It is not a tree that you’d want close to a house; it gets huge, and when it falls, its great weight can slice a house in two. So we should respect THAT if nothing else!

At the beginning of its life cycle, Cottonwood fluff released by full-grown trees – each snowflake-like poof carrying a tiny ivory seed – lands everywhere and immediately sprouts little cottonwood trees. As a tree matures, it regularly sheds branches, which often stab into the ground, sprout roots and grow new trees.

A few words on its behalf: Cottonwood grows in moist to wet conditions. It stabilizes shorelines and shades streams to the benefit of the creatures that live in them. It is a pioneer species, which means that after some kind of disturbance, say forest fire, clearing, or logging, its seeds are one of the first species to grow on the exposed soil. And they grow quickly, covering up the scars that the disturbance caused . Cottonwood consists of a great amount of biomass – leaves, constantly shed twigs and branches. Eventually the huge bulk of the whole  100-150’ tall tree – enriches the soil beneath, feeding the next plants in the line of succession. Cottonwoods that fall into streams create eddies and backwaters and shelter for fish. While it is standing, its branches provide great habitat for birds. Red-tailed Hawks, Bald Eagles and owls sit on branches near the top of the tree, surveying the countryside in search of dinner. Its crown is a favorite place for Red-tailed Hawks to nest. Deteriorating old trees and snags provide nesting cavities for birds and small mammals such as Douglas Squirrels.

In the spring, the air near Cottonwoods smells wonderful from the sticky, fragrant resin on the orange leaf buds. The resin has an antiseptic quality that Native Americans discovered. I know someone who in early spring painstakingly gathers the buds after they pop off the tree’s newly expanding leaves and makes a sweet-smelling hand lotion.

Black cottonwoods are strikingly beautiful – dark trunks and branches contrast with the brilliant green of spring leaves. The leathery, nearly heart-shaped leaves have pale, silvery undersides. In the fall the leaves turn yellow-gold on the top surface, so they really are silver and gold.

One of the most beautiful spring or fall sights which I get a chance to see on a semi-regular basis: Golden late afternoon sun sets the Cottonwoods aglow against a backdrop of dark storm clouds. The breeze from coming rain flutters the leaves making them shimmer and flash.

Next to the nursery is a field where an old Cottonwood stands. My father once told me that his mother planted it as a seedling (it probably sprouted in her flower garden!). She called it a Balm-of-Gilead Tree.

 

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*We do not use “pre-emergent” herbicide, which many nurseries apply to prevent weed seeds from germinating.

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