Three miles west of Superior on US-60, at the foot of Picket Post Mountain where Queen Creek cuts through the upper Sonoran Desert, one of the finest botanical gardens in the American Southwest has been growing since 1924. Boyce Thompson Arboretum is Arizona's oldest and largest botanical garden — 392 acres of desert landscape planted with over 12,000 plants representing more than 4,000 species from the arid lands of the world. It is also, by reputation, the most enchanting Important Birding Area in Arizona.

We visited March 21, 2026 — Matthew, Luca, and I — walking most of the trail system over the course of the day, learning about the plants, and making some connections between what we were seeing labeled and interpreted at the arboretum and what we had been seeing in the field across years of Arizona outdoor travel.

The Founder — Colonel William Boyce Thompson

Colonel William Boyce Thompson was a copper mining magnate who made his fortune in the early 20th century and chose to spend a significant portion of it on botanical research. He had served with the American Red Cross in Russia during World War I and came away with a deep appreciation for the role plants play in human civilization — as food, medicine, building material, and ecological foundation. He founded the arboretum in 1924 with the specific goal of studying and developing arid-land plants and their potential as usable resources.

The arboretum was incorporated as Arizona's first nonprofit research institution on October 5, 1927, and officially dedicated and opened to the public on April 6, 1929. It remains today what Thompson intended — a research institution, a teaching garden, and a public destination in equal measure. It was for many years an Arizona State Park — a designation withdrawn in 2019 — and is now managed by the nonprofit Boyce Thompson Southwestern Arboretum, Inc.

The Setting — Queen Creek and Picket Post Mountain

The arboretum's setting is its first remarkable feature. Queen Creek runs through the property — a riparian corridor that draws wildlife and supports the lush vegetation along the creek banks in dramatic contrast to the desert slopes above. Picket Post Mountain rises above the arboretum's eastern boundary — a volcanic remnant that gives the landscape its vertical punctuation and provides the backdrop for some of the best photography in the garden.

The microclimate created by Queen Creek's water, the mountain's shelter, and the upper Sonoran Desert elevation creates conditions that allow an extraordinary range of plant species to thrive here — from Australian acacias to South American cacti to African aloes to Mediterranean herbs, all growing within walking distance of each other in a landscape that feels cohesive rather than assembled.

The Trails — Five Miles Through the World's Deserts

Five miles of trails traverse the arboretum — a primary 1.5-mile loop connecting the major exhibit areas, with side trails branching to more specific collections and natural areas. The Chihuahuan Trail, Curandero Trail, and High Trail extend the experience beyond the main loop for those wanting more distance and elevation. Walking everything with stops takes the better part of a day — three hours is the minimum to cover the main trail with any attention paid to the plants.

The eastern section of the trail crosses undeveloped natural desert — plants in their natural state rather than cultivated exhibits. The transition between curated botanical garden and raw Sonoran Desert happens within a few steps and is one of the more instructive moments in the whole visit.

The Collections

The arboretum's 12,000+ plants are organized into geographic collections — each section representing the arid lands of a different part of the world:

Cactus and Succulent Garden — the most comprehensive outdoor cactus collection in Arizona, covering North and South American species in extraordinary variety.

Australian Exhibit — eucalyptus, acacias, and other Australian desert species. The scale of the eucalyptus grove is immediately striking.

South American Exhibit — Andean and Patagonian desert species alongside tropical dry forest plants.

African Exhibit — aloes, euphorbias, and other African desert succulents alongside the iconic baobab-related species.

Mediterranean and California Gardens — species from drought-adapted regions sharing climate characteristics with Arizona.

Sonoran Desert — Native Collection — the native plants of the Sonoran Desert, labeled and interpreted in the context of their ecological roles and relationships.

What We Identified — Connecting the Garden to the Field

One of the most rewarding aspects of visiting Boyce Thompson with a background in field plant identification is the labeled confirmation of plants seen in the wild. On our March 2026 visit we identified three plants at the arboretum that we had been seeing repeatedly in nature without being certain of the identification:

Firecracker Plant (Russelia equisetiformis) — a graceful cascading shrub with narrow green stems and brilliant red tubular flowers that attract hummingbirds. Now confirmed and named — we will recognize it immediately in the field.

Hopseed Bush (Dodonaea viscosa) — a common Arizona desert shrub with distinctive winged seed pods — the "hopseed" — that cluster on the branches. Widely used in landscaping throughout the Phoenix area but also native to the Sonoran Desert. Confirmed and named.

African Sumac (Rhus lancea) — a graceful weeping tree with dark green narrow leaves and small red berries, extremely common in Phoenix Valley landscaping and increasingly naturalized in disturbed desert areas. Confirmed and named.

The arboretum's interpretive labels make it one of the best field identification tools available for Arizona desert plants — a living reference library that clarifies things you've been looking at in the wild and wondering about.

The Clevenger House

The property inherited a two-room stone and mortar homestead built around 1900 — the Clevenger House. Rather than removing it, the arboretum incorporated it into the garden as an herb garden — planting beds of native and southern European culinary, medicinal, and cosmetic herbs surround the historic stone structure. The Clevenger House sits in the canyon section of the garden and provides a tangible historical grounding point in a place that might otherwise feel entirely botanical. The arboretum sits on what was once an active homestead — someone lived here before it became a garden.

Wildlife — Coati, Rabbit, and Cardinal

The arboretum has been identified as the most enchanting Important Birding Area in Arizona — over 210 bird species have been recorded on the grounds. The combination of Queen Creek riparian habitat, desert scrub, and the diverse planted collections creates a habitat mosaic that attracts an exceptional range of species. March is spring migration season — one of the best windows of the year for birding at the arboretum.

On our March 2026 visit we encountered a coatimundi (coati) working the garden — the long-snouted, ringtail-bearing relative of the raccoon native to the sky island ranges of southeastern Arizona and a genuinely exciting sighting in the upper Sonoran Desert location of the arboretum. A rabbit moved through the garden understory. A male Northern Cardinal — brilliant red against the desert-colored background — was one of the more photogenic wildlife moments of the visit.

A Note on the Legends of Superior Connection

The Legends of Superior Trail (LOST) runs adjacent to Boyce Thompson Arboretum on the Queen Creek corridor — the historic Pinal ghost town site and wagon wheel tracks are just down the road. The two locations complement each other naturally as a combined visit — botanical garden in the morning, archaeological history in the afternoon, or vice versa.

More Information

• Admission: Adults $15, Seniors $13, Youth (5–12) $8, Children under 5 free — check arboretum.ag.arizona.edu for current pricing

• Guided tours available — check current schedule at arboretum.ag.arizona.edu

• Birding: 210+ species recorded — Important Birding Area designation

Contact

Boyce Thompson Arboretum

37615 E. Arboretum Way, Superior, AZ 85173

(520) 689-2723

arboretum.ag.arizona.edu

Hours

Open daily 7:00 AM — check current closing time at rboretum.ag.arizona.edu

Closed Thanksgiving and Christmas

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