Quercus oblongifolia, commonly known as Mexican blue oak, is an evergreen tree or large shrub native to oak woodlands, chaparral, and pinyon-juniper communities in the southwestern United States and northwestern Mexico, including Arizona, New Mexico, Texas, and the Mexican states of Sonora and Chihuahua. It typically grows to a height of 16-26 feet (5-8 meters) and has a rounded to irregular crown. The Mexican blue oak is notable for its leathery, bluish-green leaves that are oblong to elliptical in shape. It produces inconspicuous yellowish-green catkins in the spring, followed by light brown, ovoid acorns that are valuable food sources for wildlife.

The Mexican blue oak is valued for its drought tolerance and its unique blue-tinted foliage, which adds a distinctive color contrast in gardens. It is used in xeriscaping, as a specimen tree, and in naturalistic plantings. This species is adapted to a range of soil types, provided they are well-drained, and it requires minimal supplemental water once established. It thrives in full sun to partial shade. While generally disease-resistant, it can be susceptible to oak root fungus in poorly drained soils. Its slow to moderate growth rate and compatibility with other native plants make it a low-maintenance choice for gardeners in its native range and similar climates.CC BY-SA 4.0