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)