The wonders of willows: How this hardy tree is designed to survive floods

I’ve been writing these nature columns for many years, and I hope to write them for years to come, but sometimes the writing doesn’t come easy. The other evening was one of those difficult times.

As I reached for a bottle of aspirin to alleviate a headache, it hit me — willows.

The scientific name for the willow genus is Salix, and the main ingredient in the original 1899 aspirin was salicin, an extract from willows.

I’m not going to attempt to sort through the dozens of North American willows and their confusing hybrids. I don’t have enough aspirin for that. I’d like to concentrate on two of the willow trees, weeping and black, as well as a few of the willow shrubs.

Weeping willow (Salix babylonica)

Unlike black willows, weeping willows aren’t native to this continent. The scientific name is somewhat misleading. This species originates from northern China, not the Middle East. Examples of Salix babylonica can be found growing along the famed Silk Road trade routes between China and Europe. The weeping willow arrived in Europe around 1730 and traveled to North America courtesy of colonization. The weeping willow also landed on the West Coast via Japan.

Its graceful, long, slender, drooping branches makes the weeping willow an easy tree to identify. This pendulous growth habit earned this willow its common name. Not surprisingly, the tree is a popular choice for landscapers and gardeners. It is also the choice of pollinators such as specialized bees and butterflies. If planted in full sun, this rapid grower can reach a height of 60 feet.

In addition, weeping willow tolerates soils that are somewhat acidic to alkaline. Finally, it thrives in low areas and wet spots where other trees might drown. Decades ago, my father and I planted two weeping willows in a sunny, wet pocket on the property. They grew fast and sucked up the water, just as we had hoped. You see, they are designed to do just that.

Like all willows, weeping willows are easily started from a sprig. Just stick it in some water and watch the rootlets sprout. When you think of where willows grow — along rivers, streams and other places prone to flooding — this asexual method of reproduction is a handy adaptation.

If a flood washes away a bank and there is a willow that grew on it, odds are one of its branches will end up on a spit of mud or in a shallow pool downstream. With the passage of time, that branch will take root and a new willow will be on its way.

In this country, most weeping willows are male clones and, thus, produce no fruit. Since reproduction for a willow is as easy as dropping a twig in running water, these clones can be found growing where no human planted them.

Black willow (Salix nigra)

Rather plant a native species? Then, this next tree is for you. While some may appreciate the graceful form of a weeping willow, give me the craggy old coot of the willow family, the black willow. One of the world’s largest willows, it varies in appearance with where it is growing. Along an Eastern Seaboard stream, it is a tree reaching a height of 40 to 50 feet. In the southern reaches of the Mississippi River’s flood plain, a black willow can reach a height of 100 feet in a mere 40 years.

Here at the Stillman Nature Center, we had a couple of sprawling specimens of our own. They had large forks, beginning low down, and each fork leaned outward, giving the tree a “slouching picturesqueness” as Donald Culross Peattie wrote.

Black willow has many alternate names, such as American, brittle and, a favorite of mine, scythe-leaved willow. I like it because the botanical term for willows’ long narrow leaves is lanceolate, or lance-shaped. Lances and scythes belong together, don’t you think?

Brittle is another appropriate name. Its slender, reddish-brown twigs are flexible at first. As they age, the twigs become darker and brittle at the base. Anyone who has sat at a picnic table or parked a boat under a large black willow will soon find these items decorated with fallen black willow twigs.

Unfortunately, willows are short-lived, rarely living past 85. But, as I’ve watched our willows here at Stillman, I have some questions about that figure.

For example, one of our largest black willows came down in a heap some years ago. After the chain saws were done, all that was left was the short, thick trunk and a few feet of each main branch that the trunk divided into.

Was the tree dead? Not quite. As the years passed, flexible yellow branches grew from one of the large “dead” arms. Nutrients and water were obviously flowing from the roots and through the tissues of this “goner.”

So when is a tree dead? A newspaper story provided an answer that fits our willows. The article was about the fate of a sequoia. At the time, the tree was at least 2,500 years old, “We don't know if it's dying or not,” said an interpretive ranger at Sequoia National Park. “One branch with green leaves connected by live tissue to one root is all that's needed for a tree to be considered alive.”

Of course, the sequoia’s trunk remained standing, unlike our willow’s old trunk that was down and decomposing.

Shrubby willows

Most willows don’t have large trunks since they exist as shrubs. This is not the place to sort through them all. A partial list would include goat, Bebb, narrowleaf, sandbar and, the florists’ favorite, pussy willow.

The native pussy willow (Salix discolor) is a boreal species that can occasionally be found growing in northeastern Illinois. As you might have guessed, it inhabits wet areas such as flood plain forests, marshes, and shrubby swamps.

Because willow thickets are within reach, deer, elk and domestic livestock will feed on willow leaves and twigs. This brings me back to where I started.

Peoples from North America to ancient Greece made teas and other medicines from willow bark to treat joint pain and other ailments. So, are animals eating willows just to fill their stomachs or to ease their aches and pains as well? The next time I run into a talkative deer, I’ll ask.

• Mark Spreyer is executive director of the Stillman Nature Center in Barrington. Email him at stillmangho@gmail.com.