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Today, the cactus tops out at more than 20 feet, with a pair of arms, crowned in flowers, hoisted to the sky above the desert flats of Saguaro National Park.

Tom Orum and Nancy Ferguson can tell you just about everything that has ever happened to No. 322.

The husband-and-wife science team visited this saguaro — and hundreds of others in the park’s Rincon District — every year for more than four decades.

Until this year, the retired University of ÃÛèÖÖ±²¥ researchers were the keepers of one of the longest-running annual plant surveys anywhere in the world: six, 10-acre scientific plots that have been studied continuously since 1942.

Tom and Nancy began helping with the work in 1979 and kept it going pretty much on their own since 2000.

“This has been a labor of love by two really talented and thoughtful biologists,� said longtime Saguaro National Park biologist Don Swann. “The amount of information they have gathered about the saguaro is really nothing short of astonishing.�

Last year, Tom, now 75, and Nancy, 79, decided it was time to hand the project off to the next generation of researchers. The 2022 survey was their last.

“We may be spry now,� Nancy said with a laugh, “but we won’t be spry forever.�

Bleak origins

The annual survey was borne out of desperation in 1941, just eight years after Saguaro National Monument was established.

Scientists at the time were growing increasingly alarmed by signs that the monument’s namesake cactus might be dying out. A number of research projects were launched to determine what was happening and how it could be stopped.

In one audacious experiment, every saguaro with signs of bacterial rot across a 320-acre patch of desert was chopped down, burned with kerosene and buried in a trench in hopes of halting what researchers wrongly feared was an infectious fungus similar to Dutch elm disease or chestnut blight.

The six scientific plots that are still being studied today were part of an original, 1-square-mile survey performed in preparation for that bacterial rot experiment at what is now the east end of Broadway.

Swann said most scientific studies only last a few years — the duration of a typical master’s or doctoral degree program. Longer efforts are far more difficult to sustain, as funding inevitably runs out and researchers move on.

This project almost certainly represents the longest-running annual plant survey in Park Service history, he said.

“If there’s a longer one in the national parks, I don’t know about it,� Swann said. “It’s really neat because it kind of tells the story of this plant in the park that’s named after it.�

So far, though, the story is not a happy one.

The data collected over the past 80-plus years charts population declines triggered by drought and changes to the landscape and the climate, much of it wrought by people.

Before the cactus forest was protected, nurse trees were cut down for firewood, ground cover was grazed away by livestock and natural predators were killed off by ranchers, allowing a surge of rodents to feed unchecked on vulnerable young saguaros.

Now the study area rests within a federal preserve, but it still faces an increasing onslaught of heat waves, deep freezes and long dry spells widely linked to human-caused climate change.

During the original survey in 1942, researchers mapped and counted almost 1,500 saguaros on the six research plots. All but 30 of those cactuses have since died, but only about 600 saguaros have grown in to replace them over the ensuing decades, two of which ranked as the driest 10-year periods ÃÛèÖÖ±²¥ has seen for centuries.

As Swann put it: “We’re seeing in a detailed way how we don’t get a new crop of saguaros every year.�

But what earlier scientists mistook for looming extinction might be something more basic. “Maybe this is the way saguaros work,� Tom said.

“They call it episodic recruitment,� Nancy explained. “There are really two strategies for dealing with the desert: One is to hang out and wait for the rain over a long lifetime, and the other is the spring ephemeral — make your seeds quickly and let them do the waiting.�

Saguaros have evolved to wait things out.

Aging giants

Tom and Nancy met in ÃÛèÖÖ±²¥ through mutual friends, after each of them moved here for a research job in 1974, he from California and she from Tennessee.

He is a plant pathologist. She is an ecosystems ecologist with a background in data management.

They were married in 1980, the year after Tom took part in his first saguaro survey. She joined the effort a few years later.

They were brought into the study by Stan Alcorn, a veteran University of ÃÛèÖÖ±²¥ scientist and professor who took over the project in 1955 and kept it going until his death in 1999, about a month after his last annual visit to the research plots.

Tom said Alcorn originally came to ÃÛèÖÖ±²¥ to work for the U.S. Department of Agriculture’s Research Service, where then-U.S. Sen. Carl Hayden had “set up a line item for saguaro researchâ€� to keep the plant from disappearing from the national monument.

“Saguaros weren’t establishing,� Tom said. “They had been doing the plot research since ‘41, and in ‘55 they still weren’t finding little ones.�

Alcorn’s job was to figure out why.

His tenure began with a dismal, two-decade stretch during which almost no saguaro reproduction seemed to be taking place. Year after year, acre after acre, all he found were aging giants and nothing to replace them.

That ugly period was still going on in the late 1970s, when Alcorn lured Tom to the UA for a research job and recruited him to help with the saguaro survey.

Tom said they used to head out to the plots each year when the university went on spring break, because the study wasn’t part of their official work.

“It was off the books, so to speak,� he said.

Any funding for the research ran out sometime during the Kennedy administration, when Saguaro National Monument was expanded to include the ÃÛèÖÖ±²¥ Mountain District. (Congress elevated the monument to national park status in 1994.)

Nancy wanted to be a part of the study from the moment she heard about it.

At previous research jobs, she said, you’d be lucky to get enough funding to pay for even five years of work. Here was a project that had already lasted for 35 years, with no end in sight.

“That’s an amazing thing to be able to participate in,� she said, “and, like everybody else, saguaros were something that I wanted to see more of.�

Story of 322

Nancy spent her first few surveys with Alcorn and Tom taking photos and serving as an extra pair of eyes to hunt for young saguaros.

Eventually, though, she took custody of the field books and the crucial job of jotting down every measurement and observation.

By the 1990s, Tom said, he and Nancy were essentially working the plots as a two-person team, freeing up Alcorn to concentrate on finding baby cactuses.

Nancy said Stan had a good eye for that. He was the one who first spotted No. 322 on plot C-7 and assigned it its number, 52 years ago.

The story of that particular cactus through the decades since includes an abduction, a graduation and an infestation.

In 1982, when 322 was still less than 2 feet tall, the survey team showed up to find a hole in the ground where another, slightly smaller saguaro — No. 321 — used to grow just a foot away.

“We wrote down ‘swiped,’ � Tom said.

“A technical term,� Nancy added with a grin.

The remaining saguaro reached a milestone in 1992, when 322 grew past 6 feet and officially “graduated� into the next height class.

“For a while, we were taking graduation pictures of our saguaros, but we eventually let that go,� Nancy said.

Three years later, the tip of 322’s stem was damaged by a run-in with the palo verde that sheltered it. Six years after that, the cactus sprouted its first arm.

Through it all, 322 kept growing at a robust rate, possibly fueled by the extra water runoff it gets from the nearby dirt road leading to the park’s Mica View Picnic Area. By 2003, it had outlived its nurse tree, the remains of which still litter the ground at its base.

The most recent entries for 322 include a second arm in 2018 and a bout of cactus borer moths in 2019 that left dozens of exit wounds, like acne scars, along its stem.

“I think it’s an example of what you can know about a plant if you look at it once a year,� Nancy said.

No GPS needed

In the early days, the researchers could finish the entire census over the course of two or three 12-hour days.

But once Tom and Nancy retired from their university jobs in 2000, they decided to spread the work out over about two weeks, so they could enjoy themselves out there. “It was an opportunity to go slower,� Tom said.

In late winter or early spring, they would set out for one of their scattered plots with the tools of the trade in hand: maps, field journals, a compass, a carpenter’s ruler and a tape measure. They would use a clinometer to gauge the height of their tallest specimens. For mid-range cactuses, they’d use a 12-foot length of plastic pipe they nicknamed Charlotte.

“The PVC was probably made in Charlotte, North Carolina,� Tom said with an embarrassed chuckle. “It just said ‘Charlotte’ there on the pipe.�

To get to one of their research areas, they had to hike about a half a mile up and over two ridges, but they never carried a GPS unit with them because they didn’t need it.

“Tom in particular finds the plots by recognizing the saguaros,� Nancy said.

“That is a great pleasure to know the landscape well enough to just go out walking a half mile and say, ‘yeah, we’re here,’� Tom said.

They would start by finding a saguaro they knew near one corner of the plot, then confirm it with the map and any identifying details recorded in the field book.

From there, they would work their way from cactus to cactus, recording their heights, general condition and distinguishing features — everything from bird holes and lightning strikes to new arms or soon-to-be arms they referred to as “nubbins.�

The process typically took about five minutes per plant, and included the occasional surprise.

“Over a couple of years, we were able to document a hailstorm,� Tom said. “We could see the scarring from the hail just on one side and only up to a certain point. Then, as the saguaro grew, the scarring stopped.�

Discovering a new young cactus was the ultimate thrill, but it wasn’t easy. It can take 10 years for a saguaro to grow just an inch or two, and the ones that seem to do the best are usually tucked away underneath a tree or bush.

“You could walk right by them and not see them,� Tom said.

Other times, they would stumble across obvious ones they had somehow missed for several years in a row.

“They were called embarrassments,� Nancy said.

“As in, ‘How could we not have seen that?’ � Tom added with a laugh.

Lifetime of work

Earlier this month, Saguaro National Park honored Tom and Nancy for their lifetime contribution to science.

Swann nominated them for the award, which is named after Ray Turner, a groundbreaking desert ecologist and author who popularized the use of repeat photography to reveal changes in vegetation in the cactus forest and elsewhere.

The park has only given out the honor one other time, to Turner himself in 2016.

Swann remembers the first time he joined Tom and Nancy on one of their annual surveys about 15 years ago.

“I learned so much from just going out in the field with them,� the seasoned park biologist said. “They knew all these saguaros personally. I was blown away.�

Their study is now in Swann’s hands. He and fellow Saguaro biologist Kara O’Brien officially took it over last year, and conducted the survey themselves for the first time a few months ago.

Tom and Nancy are thrilled with the project’s new caretakers. Putting the research plots in the hands of the park’s own scientists was the best and most obvious choice.

“We feel really lucky that Don and Kara are going to carry it on for a while,� Tom said.

“It wasn’t like it was onerous and we were trying to get rid of it. It was something we enjoyed,� Nancy added. “But it is wonderful to have it valued by the park and to have them pick it up.�

As it turned out, the couple timed their handoff perfectly.

Last September, Tom got an infection in his knee that required surgery and a spell in a wheelchair. He was still using a walker when survey time rolled around.

“We couldn’t have done it this year,� Tom said, “but there was Don and Kara, and they did it, which was amazing.�

“We were wiping our brows,� Nancy said.

Ultimately, Tom said, his wife deserves the credit for making sure they kept the survey going for as long as they did.

“She was a real proponent of how important it was,� he said. “Come spring, there wasn’t any question about what our priority was.�

Nancy said they still joke about whether the study “motivated the marriage� or the other way around.

In 2016, the couple teamed up with a third researcher for — published in the peer-reviewed, open-access journal PLOS ONE — based on their decades of work in the field.

Both scientists believe there are more discoveries waiting to be made from the data that’s been collected from the plots over the past 80 years. They also think there is a lot to learn from keeping the survey going long into the future.

Despite the project’s already eye-popping length, Nancy said a few more generations of researchers may be required to finish something unprecedented: a complete and detailed picture — in one-year increments, at least — of a single saguaro’s entire lifespan from establishment to death.

“We’ve got this group now of 600 that have been measured every year since they were found, and the park has the opportunity to carry them until they die,� she said. “Then there will be actual numbers on how long those saguaros live.�