Boyce Thompson Arboretum is Arizona’s oldest and largest botanical garden.
The 378-acre Boyce Thompson Arboretum (BTA) sits at the foot of Picket Post Mountain and is bordered by Highway 60. It is three miles from the small mining town of Superior, Arizona. Colonel William Boyce Thompson, who made his fortune in mining, founded the Arboretum as arguably the world's first dry lands arboretum. The mission of the arboretum is to study plants from sub-arid regions around the world, so it is also home to about 20,000 plants of 4,025 taxonomic species (about 30% of which are rare and endangered) from around the globe. The garden contains plants from the United States, Mexico, Australia, Madagascar, India, China, Japan, Israel, South America, the Middle East, Africa, the Mediterranean, and the Arabian Peninsula.
It may seem paradoxical that a man who made his riches mining would have a soft spot for the environment. Still, Thompson grew up gardening as a boy in Montana and, from a young age, observed how the fumes from copper smelting damaged his crops and vegetation. As a member of an American Red Cross relief mission, he visited Russia before and after the Russian Revolution, earning the honorary title of Colonel from the Red Cross. Traveling through Siberia, he observed the ingenuity of locals who survived on scarce vegetation in an arid land, showing the potential of arid plants to solve food supply shortages. This inspired him to create the Boyce Thompson Institute for Plant Research in Yonkers, New York (now at Cornell University), to investigate the potential that plants had for the betterment of mankind. He continued this mission by establishing an arboretum in the Sonoran Desert he had come to know and love. His intentions were ambitious, stating, “We will bring together and study the plants of the desert countries, find out their uses, and make them available to people."
Officially incorporated as Arizona’s first non-profit research organization in 1927, Boyce Thompson Arboretum opened to the public in 1929. Constructed in the shadow of the Picket Post mansion, Colonel Thompson’s winter home, the arboretum was closely associated with the University of Arizona throughout its history. In 1965, the arboretum entered into an official partnership with the University to establish the Desert Biology Station and further research efforts. In 1976, the Arboretum and the University of Arizona entered an agreement with Arizona State Parks, where the Arboretum would be simultaneously a non-profit research center and a State Park. This agreement lasted until 2019, when the Arboretum once again became an independent non-profit.
Its modern mission echoes the sentiments of Colonel Boyce Thompson as it strives to “inspire appreciation and stewardship of desert plants, wildlife, and ecosystems through education, research, and conservation.” Its dedication to sustainability can be seen in the arboretum, which functions as a living museum open to the public and researchers to learn from the rich ecosystem. Research on medicinal uses for plants, geographic surveys, and wildlife studies occur on the same trails as bird watching and elementary school field trips.
BTA houses nationally accredited collections of eucalyptus trees, desert legumes, and southwest oaks. It also houses the country’s largest longneck eucalyptus, “Mr. Big.” At 177 feet tall and with a circumference of over 22 feet, Mr. Big was added to the National Register of Champion Trees in 2018. He immigrated from Australia at three in 1926 when he was just six feet tall. He is 100 years old and happily rooted adjacent to his wife (a eucalyptus), Mrs Big.