a massive weeping elm tree showing off fall colors on the Regis campus

The Arboretum at Regis

Welcome to the Arboretum!

An arboretum is a type of botanical garden focused on trees and shrubs. Around the world, arboreta support scientific research and conservation, offer education and community programs, and care for diverse, visually rich collections of trees. The Regis Arboretum is a living library that is open to the public, providing beauty and environmental benefits for our campus community and the surrounding neighborhood.

We hope you can join us on our Denver campus to experience the majesty of our trees firsthand. But if you can't join us in person, please take some time to explore our interactive Arboretum map. The map displays a list of many of our most prominent trees, including common name, genus and species. Many trees also feature photos and in-depth tree stories so you can get to know each individual tree. And, if you know what tree you'd like to see? Our map allows you to search and filter by keyword, and will provide walking directions to specific trees.

Jump to: Champion Trees | Arboretum History | Commemorative Trees | Tree Endowment

illustration of a map of the Regis campus

Our Champion Trees

A champion tree is recognized as the largest or most impressive of its species in a specific geographical region. The designation is given by the Colorado Tree Coalition and is based on measurements like height, trunk size and crown spread. The Regis Arboretum is home to at least 28 champions that come from within the state of Colorado, but that list changes regularly when trees grow or die, or when new champions are discovered.

American Hornbeam

Amur Chokecherry

Black Oak

Blackjack Oak

Blue Atlas Cedar

Carpathian Walnut

Cedar of Lebanon

Chinese Zelkova

Contorted White Pine

Corneliancherry Dogwood

Cutleaf European Beech

Cutleaf Silver Maple

Hall's Hardy Almond

Heritage River Birch

Jack Pine

Paperbark Maple

Pin Oak

Rivers Purple-leaf Beech

Saucer Magnolia

Sawtooth Oak

Silver Linden

Spike-leafed Maple

Tanyosho Japanese Red Pine

Tricolor Beech

Weeping American Elm

Weeping Blue Spruce

Weeping European Beech

Arboretum History

Started in 2002, the Arboretum at Regis University initially contained only 200 trees. Today, it consists of more than 1,600 trees, 94 genera and more than 410 species or cultivars.

Explore Arboretum History

A History of the Arboretum

When Regis University arrived at its new campus in 1887, the land was virtually devoid of trees and woody shrubs, much like the rest of the region except along a few permanent waterways. Over the following century, campus plantings developed painstakingly, as they did throughout the Front Range, despite the challenges of the fickle, semiarid High Plains environment.

The Regis Arboretum began taking shape much later, in the mid- to late 1980s, adding to the diversity of the campus’s established plantings. Fr. Jack Callahan, S.J., a University administrator with a passion for botany and especially arboriculture, took the first steps. He planted unusual tree species obtained through mail-order sources and scoured local nurseries for the occasional orphaned sapling.

A short time later, Regis hired horticulturist Marita Tewes, who also recognized the potential to build a true arboretum: a collection of woody plants maintained for scientific and educational purposes. She continued building on Callahan’s work.

Over the following years, the tree collection grew. Some species were rare, while others, though less rare, were uncommon or unproven in the region at the time. Today, some of those early plantings have prospered to become Colorado champion trees, recognized by the Colorado Tree Coalition as the largest of their species in the state. One of the best examples is the champion sawtooth oak on Boettcher Commons. Once an unheard-of species in the region, it began as a spindly sapling planted by Callahan.

Since the 1980s, the University’s steadily growing tree collection has received the support of many people, including Martin Hart, a member of the Regis University Board of Trustees. Hart provided funding to identify, catalog and tag the woody plants on campus and to construct the Arboretum Kiosk near parking lot 4.

This work culminated in the arboretum’s official designation during a dedication ceremony held in conjunction with the Mass of the Holy Spirit in September 2000. After more than another decade and a half of acquiring new species, the arboretum reached a new professional milestone in 2018 when it received Level II accreditation from ArbNet, an international network of arboreta administered by The Morton Arboretum near Chicago.

As of 2026, the Regis University Arboretum includes an estimated 440 distinct tree species, hybrids and cultivars, along with more than 100 species of woody shrubs. Much of the arboretum’s expansion over the past several decades was overseen by Patrick Schlanger. As Director of Regis Physical Plant Operations, Schlanger’s responsibilities included campus landscaping. Many others, including Regis employees, volunteers, academics and green industry leaders, also contributed greatly to the arboretum’s development.

Today, the tree collection provides a beautiful, naturalistic setting for the campus. Spectacular mature specimens serve as focal points near major buildings. These include the champion tricolor beeches near Carroll Hall and St. John Francis Regis Chapel, the saucer magnolias near Carroll Hall and the Felix Pomponio Family Science Center and the tanyosho Japanese pines near Claver Hall. There is also the magnificent American weeping elm near O’Connell Hall, an unforgettable sight for those who visit it.

The arboretum’s research and educational functions are equally important and reflect Regis’ Jesuit teaching traditions. Guided tours have welcomed groups ranging from elementary schoolchildren and retirees’ garden clubs to the National Association of State Foresters. Some plantings are designed to reflect regional ecology, including the Colorado native trees near the O’Sullivan Fine Arts Center.

Over the past 10 years, the University has experimentally planted a wide variety of drought-adapted tree species in hopes of demonstrating new options for chronically drought-stressed cities. The arboretum has also received donations of promising cultivars from commercial nurseries, allowing their ability to withstand the region’s often harsh climate to be tested. In addition, it serves as an ex situ repository for more than 10 tree species of conservation concern, most of which are native to North America.

Many of the arboretum’s trees have unique histories of their own. Some were already large when they arrived. The four Norway spruces now located east of Residence Village, for example, were successfully transplanted in 2003, which was neither an easy nor inexpensive task.

Several large deciduous trees were also moved to the north side of Carroll Hall in 2004 to make way for the construction of St. John Francis Regis Chapel in 2005. They included a Chinese chestnut, a Carpathian walnut and a European beech, all of which continue to thrive in their new locations.

Other trees have deep cultural connections. A Japanese white pine at the Coors Life Directions Center was planted by the Dalai Lama and Schlanger. Many of the arboretum’s trees also hold intensely personal significance for past and present Regis students and employees, as well as anyone else who has spent time on the University’s campus.

Fast Facts

1600

We estimate that there are at least 1,600 trees on our Denver campus

At least 96 genera are represented in the Arboretum

440

440 different tree species thrive on the Regis campus

Commemorative Trees

Donors who wish to give $1,500 for a commemorative tree get to choose from a list of tree species and locations on the Arboretum master plan. Then, a custom-made 6x12-inch bronze plaque, engraved with a personalized message, is installed near the base of the tree.

Tree Endowment

Currently, a small endowment provides enough funding to purchase a few trees each year, keep them labeled and update the Arboretum maps. We appreciate any additional support to keep the Arboretum thriving.

Ways to Give

Your donation is vital. It doesn't just help the arboretum flourish; it ensures this beautiful space continues to be enjoyed by generations of visitors. Whether you contribute to our general fund or make a commemorative gift to help plant a new tree, every donation is deeply appreciated and makes a direct impact.

Click Here to Make an Impact Today

Sonia John smiles for a photo while with the trees of Regis

People of the Arboretum

Since 2015, Sonia John has personally funded and cared for hundreds of trees in a campus nursery named in her honor. Under her guidance, the Arboretum has significantly accelerated its planting efforts, increasing diversity, health and beauty.

Discover Sonia's Story

If you want to improve the world, plant a tree.
Pat Schlanger, Arboretum Staff

Thanks to Our Donors and Supporters

The Arboretum would not be what it is today without the generosity, dedication and expertise of our donors, volunteers, advisors and many other supporters. Their contributions have helped shape and sustain this vibrant landscape. We are deeply grateful for their ongoing commitment and extend our sincere thanks for all they have done to help the Arboretum flourish.

Contact Regis Arboretum

Location: Regis Denver Campus

Hours: Dawn to Dusk

Contact: physplan@regis.edu | 303.458.4348