Mast Arboretum, Botanical garden at Stephen F. Austin State University in Nacogdoches, Texas, United States

Mast Arboretum is a 10-acre arboretum and botanical garden on the Stephen F. Austin State University campus in Nacogdoches, Texas, one of four main gardens on the campus. It contains more than 3,000 plant species in 20 theme gardens, including butterfly, conifer, fern, herb, heritage, and holly gardens, a pitcher plant bog, an Asian valley, a beehive exhibit, and a vine collection. The 8-acre Ruby Mize Azalea Garden, created between 1997 and 2001, holds some 7,000 azaleas, 200 camellias, 200 Japanese maple varieties, 180 hydrangea varieties, and 400 other rare ornamental trees and shrubs.

Mast Arboretum began in 1985 as a landscape plant materials class project at Stephen F. Austin State University. Its collections have grown through exchanges with the Arnold Arboretum, the United States National Arboretum, the North Carolina State University Arboretum and others. It is one of four main gardens on the campus.

The arboretum's name honors the Mast family, but the sources do not record the original landowner's name. Visitors can see the Ruby Mize Azalea Garden, created between 1997 and 2001, which holds about 7,000 azaleas, 200 camellias, 200 Japanese maple varieties, and 180 hydrangea varieties. The garden is open daily without charge.

Access is free and available daily, allowing visitors to explore the different garden sections at their own pace. The site is easy to walk through and offers shaded paths as well as open areas for strolling.

The arboretum partners with respected institutions like Arnold Arboretum and the United States National Arboretum, exchanging plants to expand its collection. These partnerships allow it to display rare and specialized species that would otherwise be difficult to find in one place.