A flower from a campus Calabash tree, one of only three in Tucson (Photo: UA Campus Arboretum)
A flower from a campus Calabash tree, one of only three in Tucson (Photo: UA Campus Arboretum)

The UA's Treasury of Exotic Trees

The Campus Arboretum is home to hundreds of plants from around the world, some of which cannot be found anywhere else in Tucson.
Dec. 2, 2015
A Calabash tree outside the main library (Photo: UA Campus Arboretum)
A Calabash tree outside the main library (Photo: UA Campus Arboretum)
A flower from the University's Golden Shower tree, located outside the Nugent Building (Photo: UA Campus Arboretum)
A flower from the University's Golden Shower tree, located outside the Nugent Building (Photo: UA Campus Arboretum)

The University of Arizona is known not only for its academic excellence and strong athletic program, but also for its sizable collection of unique trees.

Take the Cassia fistula, for example, commonly called the Golden Shower tree. Its abundant, bright-yellow blossoms are embraced by many in its native habitat of India and Southeast Asia, making it the state tree of Thailand.

Or perhaps the Crescentia alata, commonly called the Calabash tree. Native to Central America and the Mexican tropics, its fruit has anti-inflammatory properties and is often hollowed out and then dried to serve as drinking vessels — or even musical instruments.

Both of these species are one of a kind on the UA campus and do not grow anywhere else in Tucson.

They are just two examples of the hundreds of unique tree species on campus, some of which are part of microclimates.

"We have plants that represent every continent that has trees," says Tanya Quist, director of the UA Campus Arboretum.

This diversity bolsters the UA's research opporutunies, and it also has symbolic value for Quist.

"This biological diversity mimics the cultural diversity we want to welcome at the University as a land-grant school," she says. "Really, the land-grant mission is about being inclusive, extending University resources out to the community and the world at large."

But how did so many exotic trees come to be on our campus in the first place?

The story begins back in the late 19th century with the opening of the school.

From the beginning, the University imported various trees for research. Originally, the goal of this research was economic development through agriculture. Over time, the focus shifted to urban development and resource conservation.

"Trees from around the world were tested on campus either to see if they could be introduced into the state as an agricultural commodity or if they could provide some urban forest in our growing cities," Quist explains.

"And those that were not successful, we have the only one of its kind. That's the short version of how we got all these crazy trees here."