Leafing Out

Curse the annual arboreal drudge, but don’t forget to love your oak trees, too.

Illustration by Robert Meganck

Here is the mathematical formula for calculating the number of leaves you can expect will fall from your oak trees every autumn: Take all the grains of sand on all the world’s beaches. Multiply by the square root of infinity. Round to the nearest quadrillion.  

Got that number?

It’s more.

Marginally more accurate, sources around the Internet offer a figure of anywhere from 200,000 to a million leaves per oak tree. But the essential point is that anyone who has ever raked, mowed or blown a yard full of oaks can decidedly say that the answer is “a lot.”  

Yet for this smallish cost in annual service, oaks reward us with a tremendous natural bounty all year long. Food and shelter for many different species, they are also, aesthetically speaking, ever-pleasing: casting shade in summer, blazing bright with fall, etched against a winter sky, and leafing out green with the spring. It’s no surprise that Americans voted, and Congress officially designated, the oak as our country’s national tree 10 years ago this November—oaks are the stalwart reliables of the tree world, the byword for great and grand, for mighty and towering, for steady perseverance, the enduring metaphor irresistible to every author of the classroom-poster canon.

“Oak,” of course, is a broad term for a number of different trees grouped under the genus quercus. White oak, red oak, pin oak, willow oak and live oak are some of the common species found in the Commonwealth, and each has its own particular characteristics. The Southern live oak, for example (appropriately named Quercus virginiana) is known for being nearly evergreen and for its massive spread, with huge sweeping branches; in the right conditions, the crown of one of these trees can reach a diameter of as much as 150 feet.

The fast-growing and hardy willow oak can get enormous as well. Two of the four Virginia oak trees ranked among 2013’s “National Champion” trees by the nonprofit National Forests’ Big Tree program are willow oaks: One in Eastville is 105 feet tall and 328 inches in circumference with a crown spread of 137 feet, and another in Chesapeake is 131 feet tall and 301 inches in circumference with a crown spread of 130 feet.

The white oak, another oak that can grow to more than 100 feet, is a prolific acorn producer. It takes about 30 years for an oak to begin producing acorns, but in a bumper year, a mature white oak can drop as many as 20,000 of them—a boon for wildlife from white-tailed deer, black bear and wild turkey down to tiny deer mice and woodland voles.

Which is why last autumn’s mysterious absence of acorns has been a subject of statewide concern.

In my neighborhood, graced as it is with an abundance of towering oaks, the usual soundtrack of autumn suggests a catastrophe in a ball-bearing factory. The least shiver of a breeze sets loose a rattling cascade of acorns pinging off cars and tumbling down rooftops.

This fall, however, a strange silence pervaded, the usual racket wholly absent. There were no acorns. Not a few, not a handful, not a smattering—none. Nada. Zilch.

The same was true throughout the Commonwealth. No acorns. But why were there no acorns?

A press release from the Department of Forestry and Department of Games and Inland Fisheries last fall noted that acorn crops can vary widely from year to year, influenced by factors such as insects, natural cyles—2012 happened to have been a very big year for acorns—and the weather. Last year’s wet, cold spring, for example, might have been the culprit.

I blame those wretched inchworms, a.k.a. fall cankerworms, which for two years running have virtually denuded whole acres of oaks, forcing the trees to entirely re-leaf and thus (so my theory goes) sapping all the energy that would have gone into making acorns. I ran the theory by David Terwilliger, area forester for the Virginia Department of Forestry, who agreed the ravening worms could have been a factor.

“The defoliation by the worms in some neighborhoods, I am sure, had a negative impact,” he says, “given the amount of energy it takes for a giant mature tree to make new buds and then produce a new crown.” He also pointed out that stress can cause a tree to produce more acorns, biology’s imperative for survival at work. So: mystery unsolved.

The official botanical term for acorns is “mast,” which broadly means “forest tree nuts on the ground.” Is it coincidence that “mast” is also the word for the towering spires of sailing ships so often made from oak?

Actually, yes, it is an etymological coincidence, yet it is true that oak has been a favored wood for everything from shipbuilding to hardwood flooring. While hickory, pecan and maple are, relatively speaking, harder woods, oak is by far the more abundant species in the U.S., and in Virginia, according to the Department of Forestry, oak is in many parts of the state the most abundant hardwood.    

Oaks being so common, it might be easy to take them for granted. But it is worth pausing to gaze up and appreciate their venerable grace and enduring beauty.

Because you’ve got some time to kill now anyway, right? Leaf season won’t be back for another 10 months.

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