''Quercus ajoensis'' is an uncommon North American shrub with the common name Ajo Mountain shrub oak. It has been found in

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

mountain ranges of the Colorado desert, and Arizona uplands of the

Sonoran desert The Sonoran Desert ( es, Desierto de Sonora) is a desert in North America and ecoregion that covers the northwestern Mexican states of Sonora, Baja California, and Baja California Sur, as well as part of the southwestern United States (in Arizona ...

. ''Q. ajoensis'' integrates with '' Q. turbinella'' and is difficult to determine specimen identification due to hybridization. It appears that this species is an elevation variant of ''Q. turbinella'' and is best treated as a subspecies or variety as it has been treated in the past. The status of ''Q. ajoensis'' as a species is probably unnecessary due to complete integration with ''Q. turbinella'' or it being a low elevation variant of ''Q. turbinella''. ''Q. ajoensis'' is usually a

shrub A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees ...

but occasionally attains the stature of small trees up to 3 metres (10 feet) tall. The

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

are narrowly egg-shaped, up to 5 centimetres (2 inches) long, with sharp pointed teeth. The species is named for the Ajo Mountains in western

Pima County, Arizona Pima County ( ) is a county in the south central region of the U.S. state of Arizona. As of the 2020 census, the population was 1,043,433, making it Arizona's second-most populous county. The county seat is Tucson, where most of the population ...

, southwest of the town of Ajo. The species does not occur as an identifiable species outside the Ajo mountain range and most specimens are of integrated types with ''Q. turbinella''. The word "ajo" is Spanish for "garlic."

References

External links

photo of herbarium specimen at Missouri Botanical Garden, collected in Arizona in 1952
{{Taxonbar, from=Q6322733 ajoensis Flora of Arizona Plants described in 1954 Flora of Baja California Sur Oaks of Mexico