Joshua trees at Joshua Tree National Park in California. Photo by Dana Wilde

On my birthday, we drove into the Mojave Desert to look at Joshua trees. I thought they were strange, and old, and wanted to see them close up.

They’re pretty strange, at least to the eye of an old guy who lived most of his life in coastal and central Maine. They look sort of like a cross between a cactus and a red pine. They’re a succulent (meaning they have fleshy parts) with leaves similar to an aloe vera plant’s, to store water.

Mature Joshua trees, aka yucca palms, have a heavily barked woody trunk and branches tipped with brushes of those fat green blades. Common wisdom holds they may have been named Joshua trees by Mormons who while crossing the desert thought they resembled the biblical character Joshua raising his arms to pray and, in their imagination, guiding the Mormons to the promised land.

I can see that. There is something otherworldly about them. To my non-desert eye, anyway.

It turns out they are mainly not unduly old, as trees go. Most reliable online sources indicate they are thought to live around 150 years, and sometimes up to 500 years. What I had mistakenly generalized from, when I suggested we go to the Joshua Tree National Park, was a report about a Joshua tree estimated to be 1,000 years old. But that tree is located miles west of the park, and its age is unusual.

What I really had in mind was to compare the ancient Joshua tree to what I knew of the possibly oldest living being on Earth, a bristlecone pine nicknamed “Methuselah.” That tree is thought to be about 4,600 years old and still growing in the mountains of Inyo County, California, north of the park and Palm Springs (where we were providentially staying when the temperature hit minus 23 at our house in Troy a couple weeks ago).

Anyway, it turns out “Methuselah” might not be the oldest living Earth-being either. In 1964 another bristlecone, “Prometheus,” was cut down by a graduate student who wanted to count its rings. At least we know it was somewhere around 4,900 years old when it was killed. (The details of this incident are murky, but at minimum more complicated than simple academic vandalism.) If the botanists are right, “Methuselah” and “Prometheus” were already more than 2,700 years old when Christ was walking to Jerusalem. Suspected to be older still is a Patagonian cypress in Chile that researchers estimate could be 5,400 years old.

If you believe the timelines, that tree was already about 900 years old at the time the pyramids were built at Giza, an Egyptian city on the west bank of the Nile, near Cairo.

There are 1,000-year-old olive trees in the garden of Gethsemane, some of which are thought to have grown from cuttings from trees under which Jesus and the apostles prayed. Elsewhere, there are California sequoias that are up to 3,000 years old, and redwoods more than 2,200 years old. These sequoias, redwoods, bristlecones and lower-elevation Joshua trees are dangerously stressed by drought and rising temperatures.

Back East, there are bald cypresses in North Carolina that might be 1,500 years old, and white cedars in northwestern New York thought to be more than 1,000 years old. There are 400-year-old oaks near Boston, and 300-year-old white pines in Norway, Maine, that were standing when my ancestors first arrived at Boothbay.

Seems like only yesterday. Meaning, all this is highly, highly relative.

The lifespans of the bristlecones and Patagonian cypresses seem long compared to that of a Joshua tree, which seems long compared to that of a human. But, no one can confidently state the age of a quaking aspen (which we call popple). Its preferred reproductive process is clonal, meaning it throws shoots up out of a root system that can live tens of thousands of years. Is the individual trunk that dies the tree, or is the root system that lives indefinitely the tree? Not to mention bacteria, which don’t have anything like a “lifespan”— they just keep dividing. No one has ever seen a bacterium grow old and die.

I wonder how a tree experiences time. Maybe a lifetime to a tree is less like a length and more like a waft. Like an oscillation, cold to warm, dark to light, light to dark, warm to cold. Like a chime ringing seasons. Or like a reverence.

Einstein figured out that a length of time varies according to how fast you’re traveling and how close you are to gravitation. It’s not an objective flow. It’s subjective.

Happy 70th birthday to me, who’s the strange old one. I wonder what comes next.

Dana Wilde lives in Troy. You can contact him at dwilde.naturalist@gmail.com. His book “Winter: Notes and Numina from the Maine Woods” is available from North Country Press. Backyard Naturalist appears the second and fourth Thursdays each month.