The Science behind the Oldest Trees on Earth

How experts have determined that bristlecone pines, sequoias, and baobabs have stood for thousands of years

What and where are the oldest known trees on the planet?

If you include plants that can regenerate, the upper age limit could be ten thousand years or more. Such superorganisms including the famous quaking aspen (Populus tremuloides) grove nicknamed Pando are made up of genetically identical trunks connected through a single root system that sends up new shoots over time. These clonal colonies are impossible to date with precision because the oldest decomposed long ago.

Aspen clove in Fishlake National Forest © Rex Vogel, all rights reserved

Known as the Trembling Giant, Pando is located about 40 miles southeast of Richfield, Utah, the nearest town. Widely considered the world’s largest tree with one vast root system, the aspen clone is also one of the largest living organisms on the planet. Spanning roughly 106 acres within Fishlake National Forest, a sprawling patch of greenery situated in the High Plateaus of south-central Utah, Pando weighs more than 6,600 tons and contains approximately 47,000 genetically identical stems (or branches), experts say.

Pando which in Latin translates to I spread is so massive that satellite imagery shows the outline of the clone in stark contrast with the rest of the surrounding national forest; its complex network of roots is so vast that it tunnels beneath Utah State Route 25, a winding two-lane highway that slices through Pando’s center.

No one knows Pando’s exact age with some estimates dating it to the end of the last ice age or about 25,000 years ago and others going as far back as 80,000 years.

The Big Tree © Rex Vogel, all rights reserved

The Big Tree, as it’s usually known, is one of the best known live oak trees in the United States. In its more than 1,000 years, the Big Tree has survived hurricanes, fires, and even an 1864 Civil War battle that razed the rest of the town, Lamar, Texas, to the ground. With a height of 44 feet, trunk circumference of 35 feet, and crown spanning roughly 90 feet, the massive coastal live oak has survived Mother Nature’s fiercest storms including Hurricane Harvey (August 25, 2017).

Many lists of oldest trees stick to single-trunked plants that produce annual growth rings. These kinds of trees are easier to date. Scientists called dendrochronologists focus on assigning calendar years to tree rings and interpreting data within those rings. By using a hand-cranked tool called an increment borer they extract core samples without depriving the tree of strength and vigor.

Giant cypress in Congaree National Park © Rex Vogel, all rights reserved

As a rule, gymnosperms—flowerless plants with naked seeds—grow slower and live longer than angiosperms, flowering plants with fruits. Gymnosperms include ginkgo and every kind of conifer—including yews, pines, firs, spruces, cedars, redwoods, podocarps, araucarias and cypresses. Roughly 25 gymnosperm species can live 1,000 years or longer. The cypress family contains the most millennials but the longest-lived species is a pine with an effective age limit of five millennia. By contrast, eight centuries is extremely old for an oak, an angiosperm. And only one kind of flowering plant, a baobab, has been positively dated beyond one millennium.

During research for his book Elderflora: A Modern History of Ancient Trees, Jared Farmer learned a lot about the world’s oldest growers. Here are some of the most exceptional specimens.

The longest-lived gymnosperms

Bristlecone pine at Grand Canyon National Park © Rex Vogel, all rights reserved

Great Basin bristlecone pine, Pinus longaeva, ≥4,900 years

Until 1964, the oldest tree ever known grew in a cirque on Wheeler Peak in Nevada’s Snake Range in what is now Great Basin National Park. After a graduate student researcher tried and failed to extract a complete core sample, he decided to produce a stump. This scientific desecration haunted him the rest of his career even though he cut it down with permission of a forest ranger. Originally labeled WPN-114 this pine was posthumously renamed Prometheus.

The oldest survivor with a name is Methuselah which grows in the Ancient Bristlecone Pine Forest in the White Mountains of eastern California. This pine was originally cored by tree-ring scientist Edmund Schulman who made bristlecones famous through his 1958 article in National Geographic. The innermost rings on Schulman’s core samples are extremely suppressed and partly eroded making dating difficult. The oldest extracted ring from Methuselah might be from 2490 or 2555 BC. In any case this tree is well over 4,500 years old today.

Methuselah’s location is no longer marked by the U.S. Forest Service but anyone who hikes the trail will be close to it and many other living beings as old as the pyramids of Giza. In the same population an unnamed bristlecone even older than Methuselah grows and it is known only to an inner circle of dendrochronologists. Secrecy provides protection from vandals who would carve names on it, relic hunters who would take cones from it, and photographers who would inadvertently damage the fragile soil.

In a deeper sense, the identity of the true oldest living bristlecone is simply unknowable. That’s not just because no one has the time—or the funding or the imperative—to do an exhaustive search throughout the Great Basin. The effort would be futile. On most ancient bristlecones, the oldest wood has long ago been ablated, speck by speck, by desert winds.

Giant sequoia in Sequoia National Park © Rex Vogel, all rights reserved

Giant sequoia, Sequoiadendron giganteum, ≥3,266 years

As soon as Anglo-Americans encountered giant sequoia in the midst of the California gold rush, they acted in paradoxical ways: protecting them while also cutting down trophy specimens for traveling exhibits. By counting rings on stumps, people knew in the 1850s that sequoias can live for thousands of years.

After the Civil War, two of the largest protected sequoias became known as the General Grant and the General Sherman. A rivalry ensued between Fresno County, home of the Grant and Tulare County, home of the Sherman. In 1931, the California Chamber of Commerce announced an unscientific verdict: Although Sherman was—and still is—the world’s largest tree, Grant would count as the world’s oldest. Confusingly, tourists routinely referred to another monumental tree, Yosemite National Park’s Grizzly Giant as the age champion based on its incomparably gnarled appearance.

Sherman Tree © Rex Vogel, all rights reserved

In the 1990s, a forest ecologist created a mathematical formula for estimating a sequoia’s age based on the volume of its bole or the trunk below the crown. He tested his formula on hundreds of stumps in Converse Basin, the one large grove of big trees that had been devastated by industrial logging. Here, many trimillennials including the oldest ever known at 3,266 years or more had been leveled to make grape stakes and shingles. The ecologist disproved for good the old assumption that biggest means oldest. By his estimation, the General Sherman was only 2,150 years old and the Grizzly Giant was a shocking 1,790 years young.

The most senior of these trees probably lacks a name because of its relative smallness. And it may be newly dead. In 2020 and 2021, megafires devastated the southern Sierra, killing up to 20 percent of all mature sequoias.

Worth Pondering…

In their highest boughs the world rustles, their roots rest in infinity; but they do not lose themselves there, they struggle with all the force of their lives for one thing only: to fulfill themselves according to their own laws… to represent themselves. Nothing is holier nothing is more exemplary than a beautiful, strong tree.

—Hermann Hesse (1877–1962)

Explore Sequoia and Kings Canyon National Parks

Sequoia and Kings Canyon National Parks create a recreational wonderland covered by ancient forests, soaring domes, stone canyons, and rivers that roar or ripple, depending on the season

The giant trees of Sequoia and Kings Canyon National Parks will fill you with awe—and give you a crick in your neck from staring up at them. But who cares about a little pain when the payoff is so grand? And the high season is over for these two incredible parks meaning the time is right for a leisurely visit minus the crowds. And the campgrounds that are always full during the summer now have vacancies.

Eleven Mile Overlook in Sequoia National Park © Rex Vogel, all rights reserved

Shoulder-season visitors (September-November) avoid the hustle and bustle of peak times. Traffic lessens, autumn leaves appear, and it becomes easy to find a parking spot.

Forest Center in Sequoia National Park © Rex Vogel, all rights reserved

The weather also cools off, a big plus. Many days here top 100 degrees during the summer. Weather like that is brutal if you’re hiking—or even just taking a quarter-mile nature walk. Skip the sizzling July and August weather and visit in October when average highs are in the 60s.

November is a little chancier: We was here in mid-November and encountered some snow in the High Country. But, to be honest, not enough to alter our plans!

Castle Rocks in Sequoia National Park © Rex Vogel, all rights reserved

A couple of other problems also arise if you visit too late in the year. The road to Kings Canyon’s Cedar Grove area closes November 11. And you don’t want to miss that spectacular area of the park. Many campgrounds also close. But I’m getting a little ahead of myself.

Sequoia National Park © Rex Vogel, all rights reserved

Let’s start when naturalist John Muir wrote about the area that eventually became Sequoia National Park and Kings Canyon National Park. “In the vast Sierra wilderness south of the famous Yosemite Valley, there is a yet grander valley of the same kind,” Muir wrote in 1891.

Forest Center in Sequoia National Park © Rex Vogel, all rights reserved

Grander than Yosemite? Those are strong words. But many park fans agree. Sequoia has the largest trees on the planet and Mt. Whitney, the highest point in the Lower 48. Kings Canyon is by some measures considered the deepest canyon in the country.

It’s a place that can make visitors feel very small. It also can bring a sense of tranquility.

Sequoia National Park © Rex Vogel, all rights reserved

The adjacent parks, which are administered together, offer beautiful rivers and waterfalls, lush valleys, vast caverns, snow-capped peaks, and terrain ranging from 1,300 to 14,500 feet. And it’s all in the southern Sierra Nevada.

Sequoia National Park © Rex Vogel, all rights reserved

Nowhere else in the national park system can you experience the diversity of landscapes within a day’s hike, from blue oak woodlands to red fir forests to alpine tundra. Plus, the stunning ancient giant sequoia groves!

Sequoia National Park © Rex Vogel, all rights reserved

The colossal trees can grow as tall as a 26-story building and live more than 3,000 years, thanks to a chemical in their bark that protects against rot, boring insects, and even fire.

Sherman Tree in Sequoia National Park © Rex Vogel, all rights reserved

It’s hard to comprehend the size of a sequoia until you stare up at one, especially the General Sherman Tree, a giant among giants—275 feet tall and more than 36 feet in diameter. It’s the largest tree in the world by volume and is a favorite stop for visitors. Yes, you’ll have to walk half a mile to see it, but it’s a pilgrimage you’ll remember the rest of your life.

Sequoia National Park © Rex Vogel, all rights reserved

Even better: Take the 2-mile Congress Trail, which begins at the General Sherman Tree and loops through the heart of the green and beautiful Giant Forest, home to more than 2,000 sequoias with trunk diameters greater than 10 feet. It’s an easy trail and like the Sherman Trail is both wheelchair- and kid-friendly. Like no other place on Earth, the Giant Forest is alive with mystery and wonder.

Moro Rock in Sequoia National Park © Rex Vogel, all rights reserved

Another highlight of Sequoia National Park is Moro Rock, which isn’t an easy trail. If the walk to General Sherman fazes, Moro Rock will stop you in your tracks. The bald granite dome looms thousands of feet above the park highway, protruding from a forested ridge 6,725 feet above sea level.

Sequoia National Park © Rex Vogel, all rights reserved

Kings Canyon is a rugged landscape of granite, water, and sky. Like Sequoia, Kings Canyon National Park is more than 95 percent wilderness and few roads disturb the peace. But, that’s the topic of another post.

Sequoia National Park © Rex Vogel, all rights reserved

Worth Pondering…

Between Kings River and the Kaweah, we enter the colossal forests of the main continuous portion of the sequoia belt.

—John Muir, 1876