In Denver relentless sun scalds bark, ruthless snows amputate leafed-out limbs, inhospitable alkaline or clay soils starve roots, and rains refuse to fall for weeks on end. So planting a tree can take an act of faith.
Fortunately for Regis University and the public, a Jesuit priest named Jack Callahan harvested a bumper crop of belief. Callahan, formerly on staff at Regis and now at St. Louis University, planted the seed – or, more accurately, the bare root – for the Arboretum at Regis University in northwest Denver.
“There are reasons why there are no trees on the high plains; there’s every reason in the world why they don’t grow,” Callahan says.
But that didn’t stop him from trying – and succeeding. The arboretum (official since 1999) is home to more than 500 trees and shrubs of about 200 varieties, ash to zelkova. Many species and cultivars are rare to the area.
“The campus is a treasure trove of delightful plants and living proof that we really can grow a wide assortment of trees in our city,” says city forester Jude O’Connor.
She cited, in particular, the unusual forms of American elm, the exotic bald cypress, blue atlas cedar and dawn redwood.
Callahan sprouted his green thumb while trying to raise greenbacks for Creighton University, where he had served as vice president of fundraising.
“We were in the middle of a big campaign, and I was frustrated,” the priest said. “I had time off on the weekends, and I’m not a golfer, so I’d go out and trim bushes. It was good recreation.”
After arriving at Regis, he saw the potential of the 90-acre campus with the stately old brick buildings and commanding views of the Front Range. Regis, however, had seen better days.
“A lot of stuff was wasting away,” Callahan said. “The college was just coming out of real financial difficulties. I began to trim bushes again.”
And he bought plants, ordering bare roots from garden catalogs.
“One day,” he says, “on the sly, with no permission, I was digging a hole near West Hall and putting in a bare root tree when Father Clark came along.”
The Rev. David Clark, then president and currently chancellor, wanted an explanation. Clark was unimpressed with the appearance of a bare root plant, and told Callahan to get a budget to do it right.
That was summer 1984. He often would case nurseries in search of unusual trees. He remembers finding one less-than- spectacular specimen.
“It was a spindly little thing cast off in a corner. It was being sold for 15 bucks. I looked at the leaf, and it looked like a sawtooth oak, so I picked it up and put it in the ground.”
That tree now holds court on the commons, and the Colorado Tree Coalition recognized the oak as a state champion, distinguishing the tree as the largest- known species in Colorado.
Denver is not known for sawtooth oaks or Japanese umbrella trees or Chinese empress trees or Russian mullberries, but these species thrive in the arboretum, thanks to diligent tending by university groundskeepers.
With a measure of pride – not the deadly sin variety – the assistant director of operations of the physical plant, Patrick Schlanger, strides the campus pointing out yellow wood and silver linden, the exfoliating cinnamon-colored bark of an amur chokecherry. He delights in the rosette-shaped needles of a blue atlas cedar and the curly needles of a contorted eastern white pine and the variegated needles of a dragon’s eye pine.
In an area sheltered by brick buildings, a star magnolia spangled with white flowers is dwarfed by a 1997 state champion saucer magnolia just starting to sport tuliplike blossoms. A tricolored beech not yet leafed out promises pink and white and green foliage. A pin oak nearly 80 years old and a burr oak almost half a century old lend lovely structural form even when leafless. Toward one end of campus, where the university is reclaiming land formerly occupied by a Kmart, a 90-foot-tall cottonwood stands as a sentinel.
“People so often go to Home Depot and buy whatever’s on sale. A tree is an investment and needs to be thought about,” Schlanger said. “Here, people can get some different ideas.”
About 15 of the trees stand as memorials for deceased with an association to Regis. Some trees helped set the stage for the historic 1993 visit of Pope John Paul II. In 1997, a Japanese white pine was planted by the Dalai Lama.
“All these trees have stories,” Schlanger said.
Schlanger’s favorite is a weeping American elm. Another state champion, the elm is about 70 years old. Despite branch-breaker winter storms, the tree’s drip line is about 66 feet wide. Each leaf grows to about 7 inches in length.
“In summer, when it leafs out, it’s like a tent under it. It’s like an air-conditioned room,” he said.
Callahan is fond of the weeping elm too. Beneath the vast canopy of its branches, he experienced a transcendental moment when recovering from a serious and prolonged illness.
“I was in the hospital for so long, I could barely walk. When I got home, it was September or early October; and it had been a perfect season for the elm, so all the leaves turned bright yellow,” Callahan said. “I managed to get over to that tree. It’s almost like a house underneath. I remember the sun coming through gold leaves, and it was like I was living in a golden temple. It was glorious.”
